View source for Fourth Amendment to the United States Constitution

{{Short description|1791 amendment prohibiting unreasonable searches and seizures}}
{{Use mdy dates|date=January 2018}}
{{good article}}

{{US Constitution article series}}
[[File:Bill of Rights Pg1of1 AC.jpg|190px|thumb|The Bill of Rights in the [[National Archives and Records Administration|National Archives]]]]

The '''Fourth Amendment''' ('''Amendment IV''') to the [[United States Constitution]] is part of the [[United States Bill of Rights|Bill of Rights]]. It prohibits unreasonable [[Search and seizure|searches and seizures]] and sets requirements for issuing [[Warrant (law)|warrants]]: warrants must be issued by a judge or magistrate, justified by [[probable cause]], supported by oath or affirmation, and must particularly describe the place to be searched and the persons or things to be seized (important or not).

Fourth Amendment case law deals with three main issues: what government activities are "searches" and "seizures", what constitutes probable cause to conduct searches and seizures, and how to address violations of Fourth Amendment rights. Early court decisions limited the amendment's scope to physical intrusion of property or persons, but with ''[[Katz v. United States]]'' (1967), the [[Supreme Court of the United States|Supreme Court]] held that its protections extend to intrusions on the privacy of individuals as well as to physical locations. A warrant is needed for most search and seizure activities, but the Court has carved out a series of exceptions for [[consent search]]es, [[Motor vehicle exception|motor vehicle searches]], [[Plain view doctrine|evidence in plain view]], [[Exigent circumstance in United States law|exigent circumstances]], [[Border search exception|border searches]], and other situations.

The [[exclusionary rule]] is one way the amendment is enforced. Established in ''[[Weeks v. United States]]'' (1914), this rule holds that [[evidence]] obtained as a result of a Fourth Amendment violation is generally [[Admissible evidence|inadmissible]] at criminal trials. Evidence discovered as a later result of an illegal search may also be inadmissible as "[[fruit of the poisonous tree]]". The exception is if it [[Inevitable discovery|inevitably would have been discovered by legal means]].

The Fourth Amendment was introduced in Congress in 1789 by [[James Madison]], along with the other amendments in the Bill of Rights, in response to [[Anti-Federalist]] objections to the new Constitution. Congress [[Article Five of the United States Constitution#Proposing amendments|submitted]] the amendment to the states on September 28, 1789. By December 15, 1791, the necessary three-fourths of the states had [[Article Five of the United States Constitution#Ratification of amendments|ratified]] it. On March 1, 1792, Secretary of State [[Thomas Jefferson]] announced that it was officially part of the Constitution.

Because the Bill of Rights did not initially apply to state or local governments, and federal criminal investigations were less common in the first century of the nation's history, there is little significant case law for the Fourth Amendment before the 20th century. The amendment was held to [[Incorporation of the Bill of Rights|apply to state and local governments]] in ''[[Mapp v. Ohio]]'' (1961) via the [[Due Process Clause]] of the [[Fourteenth Amendment to the United States Constitution|Fourteenth Amendment]].

==Text==

{{blockquote|The right of the people to be secure in their persons, houses, papers, and effects,{{efn|Effects are items of property.<ref>{{cite web|last1=Denniston|first1=Lyle|title=Argument preview: Police and cellphone privacy|url=http://www.scotusblog.com/2014/04/argument-preview-police-and-cellphone-privacy/|publisher=SCOTUSblog|access-date=July 1, 2014|date=April 25, 2014|archive-url=https://web.archive.org/web/20230328135525/https://www.scotusblog.com/2014/04/argument-preview-police-and-cellphone-privacy/|archive-date=March 28, 2023}}</ref>}} against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.<ref>{{cite web|url=https://www.archives.gov/founding-docs/bill-of-rights-transcript|title=Bill of Rights Transcript Text|date=October 30, 2015}}</ref>}}
{{wide image|Amendment_4.jpg|1999px|The hand-written copy of the proposed Bill of Rights, 1789, cropped to show just the text that would later be ratified as the Fourth Amendment}}

==Background==
===English law===

[[File:Charles Pratt, 1st Earl Camden by Nathaniel Dance, (later Sir Nathaniel Dance-Holland, Bt).jpg|thumb|right|[[Charles Pratt, 1st Earl Camden]] established the English common law precedent against general search warrants.]]

Like many other areas of American law, the Fourth Amendment finds its origin in English legal doctrine. In ''[[Semayne's case]]'' (1604), [[Sir Edward Coke]] stated: "The house of every one is to him as his castle and fortress, as well for his defence against injury and violence as for his repose."<ref>Coke's Rep. 91a, 77 Eng. Rep. 194 (K.B. 1604).</ref> ''Semayne's Case'' acknowledged that the King did not have unbridled authority to intrude on his subjects' dwellings, but recognized that government agents were permitted to conduct searches and seizures under certain conditions when their purpose was lawful and a warrant had been obtained.{{sfnp|Kilman|Costello|2006|p=1281–1282}}

The 1760s saw a growth in the intensity of litigation against state officers, who were using general warrants, conducted raids in search of materials relating to [[John Wilkes]]'s publications. The most famous of these cases involved [[John Entick]] whose home was forcibly entered by the [[King's Messenger]] Nathan Carrington, along with others, pursuant to a warrant issued by [[George Montagu-Dunk, 2nd Earl of Halifax]] authorizing them "to make strict and diligent search for&nbsp;... the author, or one concerned in the writing of several weekly very seditious papers entitled, '[[The Monitor: Or, British Freeholder|The Monitor or British Freeholder]], No 257, 357, 358, 360, 373, 376, 378, and 380'", the search resulting in seizure of printed charts, pamphlets and other materials. Entick filed suit in ''[[Entick v Carrington]]'', argued before the [[Court of King's Bench (England)|Court of King's Bench]] in 1765. [[Charles Pratt, 1st Earl Camden]] ruled that both the search and the seizure were unlawful, as the warrant authorized the seizure of ''all'' of Entick's papers—not just the criminal ones—and as the warrant lacked [[probable cause]] to even justify the search. By holding that "[O]ur law holds the property of every man so sacred, that no man can set his foot upon his neighbour's close without his leave",<ref>''[[Entick v Carrington]]'', 2 Wils. K. B. 275, 291; 95 Eng. Rep. 807, 817 (K. B. 1765)</ref> ''Entick'' established the English precedent that the executive is limited in intruding on private property by [[English law#Common law|common law]].{{sfnp|Kilman|Costello|2006|p=1281–1282}}

==={{anchor|Colonial United States}}Colonial America===

Homes in [[Colonial history of the United States|Colonial America]], on the other hand, did not enjoy the same sanctity as their British counterparts, because legislation had been explicitly written so as to enable enforcement of British revenue-gathering policies on customs; until 1750, in fact, the only type of warrant defined in the handbooks for justices of the peace was the general warrant.{{sfnp|Kilman|Costello|2006|p=1281–1282}} During what scholar William Cuddihy called the "colonial epidemic of general searches", the authorities possessed almost unlimited power to search for anything at any time, with very little oversight.{{sfnp|Levy|1995|p=150}}
[[File:JamesOtisJr by Blackburn.jpg|thumb|left|upright|Massachusetts lawyer [[James Otis, Jr.|James Otis]] protested British use of general warrants in the American colonies.]]

In 1756, the colony of Massachusetts barred the use of general warrants. This represented the first law in American history curtailing the use of seizure power. Its creation largely stemmed from the great public outcry over the Excise Act of 1754, which gave tax collectors unlimited powers to interrogate colonists concerning their use of goods subject to customs.<ref>{{Cite journal|last=Fuqua|first=David|date=Fall 2014|title=Technology and the Fourth Amendment: History and Application of Principles of Decision in Light of New Means of Surveillance.|url=http://search.ebscohost.com/login.aspx?direct=true&db=bth&AN=97506316&site=eds-live|journal=FDCC Quarterly|volume=64|pages=2–25}}</ref> The act also permitted the use of a general warrant known as a [[writ of assistance]], allowing tax collectors to search the homes of colonists and seize "prohibited and uncustomed" goods.{{sfnp|Davies|1999}}
A crisis erupted over the writs of assistance on December 27, 1760, when the news of [[George II of Great Britain|King George II]]'s death on October 23 arrived in Boston. All writs automatically expired six months after the death of the King, and would have had to be re-issued by [[George III of the United Kingdom|George III]], the new king, to remain valid.{{sfnp|Wroth|Zobel|1965|p=113, fn 22|ps=: "The writs of assistance did not become an issue until news of King George II's death arrived in Boston December 27, 1760."}}

In mid-January 1761, a group of more than fifty merchants represented by [[James Otis, Jr.|James Otis]] petitioned the court to have hearings on the issue. During the five-hour hearing on February 23, 1761, Otis vehemently denounced British colonial policies, including their sanction of general warrants and writs of assistance.{{sfnp|Wroth|Zobel|1965|p=113, fn 23}} However, the court ruled against Otis.{{sfnp|Lasson|1937|p=57–61}} Future President [[John Adams]], who was present in the courtroom when Otis spoke, viewed these events as "the spark in which originated the American Revolution".{{sfnp|Adams|Adams|1856|p=59}}

Because of the name he had made for himself in attacking the writs, Otis was elected to the [[Massachusetts General Court|Massachusetts colonial legislature]] and helped pass legislation requiring that special writs of assistance be "granted by any judge or justice of the peace upon information under oath by any officer of the customs" and barring all other writs. The governor overturned the legislation, finding it contrary to English law and parliamentary sovereignty.{{sfnp|Lasson|1937|p=66}}

Seeing the danger general warrants presented, the [[Virginia Declaration of Rights]] (1776) explicitly forbade the use of general warrants. This prohibition became a precedent for the Fourth Amendment:{{sfnp|Levy|1995|p=161}}

{{blockquote|That general warrants, whereby any officer or messenger may be commanded to search suspected places without evidence of a fact committed, or to seize any person or persons not named, or whose offense is not particularly described and supported by evidence, are grievous and oppressive and ought not to be granted.{{sfnp|Levy|1995|p=161}}}}

Article XIV of the Massachusetts Declaration of Rights, written by [[John Adams]] and enacted in 1780 as part of [[Constitution of Massachusetts|the Massachusetts Constitution]], added the requirement that all searches must be "reasonable", and served as another basis for the language of the Fourth Amendment:<ref>{{cite web|url=http://gonzagalawreview.org/files/2011/01/45-Gonz-L-Rev-1.pdf|title=The Originalist Case for the Fourth Amendment Exclusionary Rule|last=Roots|first=Roger|page=20 (fn. 118)|date=January 13, 2010|publisher=Gonzaga Law Review|access-date=January 8, 2012|archive-url=https://web.archive.org/web/20130115121043/http://gonzagalawreview.org/files/2011/01/45-Gonz-L-Rev-1.pdf|archive-date=January 15, 2013|url-status=dead}}</ref>

{{blockquote|Every subject has a right to be secure from all unreasonable searches, and seizures of his person, his houses, his papers, and all his possessions. All warrants, therefore, are contrary to this right, if the cause or foundation of them be not previously supported by oath or affirmation; and if the order in the warrant to a civil officer, to make search in suspected places, or to arrest one or more suspected persons, or to seize their property, be not accompanied with a special designation of the persons or objects of search, arrest, or seizure: and no warrant ought to be issued but in cases, and with the formalities, prescribed by the laws.<ref>{{Cite web|url=http://www.mass.gov/legis/const.htm|title=Massachusetts Constitution|website=www.mass.gov}}</ref>}}

By 1784, eight state constitutions contained a provision against general warrants.<ref name=Cuddihy/>

==Proposal and ratification==

{{main|United States Bill of Rights}}

After several years of comparatively weak government under the [[Articles of Confederation]], a [[Constitutional Convention (United States)|Constitutional Convention]] in Philadelphia proposed a new constitution on September 17, 1787, featuring a stronger chief executive and other changes. [[George Mason]], a Constitutional Convention delegate and the drafter of Virginia's Declaration of Rights, proposed that a bill of rights listing and guaranteeing [[civil liberties]] be included. Other delegates—including future Bill of Rights drafter [[James Madison]]—disagreed, arguing that existing state guarantees of civil liberties were sufficient and that any attempt to enumerate individual rights risked implying that other, unnamed rights were unprotected. After a brief debate, Mason's proposal was defeated by a unanimous vote of the state delegations.{{sfnp|Beeman|2009|p=341–43}}

For the Constitution to be ratified, nine of the thirteen states were required to approve it in state conventions. Opposition to ratification ("Anti-Federalism") was partly based on the Constitution's lack of adequate guarantees for civil liberties. Supporters of the Constitution in states where popular sentiment was against ratification (including Virginia, Massachusetts, and New York) successfully proposed that their state conventions both ratify the Constitution and call for the addition of a bill of rights.{{sfnp|Maier|2010|p=431}} Four state conventions proposed some form of restriction on the authority of the new federal government to conduct searches.<ref name=Cuddihy>{{cite encyclopedia|url=http://www.highbeam.com/doc/1G2-3425001007.html|archive-url=https://web.archive.org/web/20130921061306/http://www.highbeam.com/doc/1G2-3425001007.html|url-status=dead|archive-date=September 21, 2013|title=Fourth Amendment, Historical Origins of|last=Cuddihy|first=William|year=1986|encyclopedia=Encyclopedia of the American Constitution|publisher=|access-date=July 27, 2013}}</ref>
[[File:James Madison.jpg|thumb|[[James Madison]], drafter of the Bill of Rights]]

In the [[1st United States Congress]], following the state legislatures' request, James Madison proposed twenty constitutional amendments based on state bills of rights and English sources such as the [[Bill of Rights 1689]], including an amendment requiring probable cause for government searches. Congress reduced Madison's proposed twenty amendments to twelve, with modifications to Madison's language about searches and seizures.<ref>"[http://press-pubs.uchicago.edu/founders/documents/amendIVs13.html Amendment IV]", ''The Founders Constitution'', University of Chicago Press.</ref><ref>Gordon, John D. (III). "Egbert Benson: A Nationalist in Congress", in ''Neither Separate Nor Equal: Congress in the 1790s'', pp.&nbsp;[https://books.google.com/books?id=NzjaxV8oDpMC&pg=PA70&lpg=PA70 69–73] (edited by Kenneth R. Bowling and Donald R. Kennon of the United States Capitol Historical Society, published by Ohio University Press in 2000).</ref> The final language was submitted to the states for ratification on September 25, 1789.<ref>{{cite web|url=https://www.archives.gov/exhibits/charters/bill_of_rights.html|title=Bill of Rights|publisher=National Archives|access-date=April 4, 2013|archive-date=April 4, 2013|archive-url=https://web.archive.org/web/20130404123122/http://www.archives.gov/exhibits/charters/bill_of_rights.html|url-status=live}}</ref>

By the time the Bill of Rights was submitted to the states for ratification, opinions had shifted in both parties. Many Federalists, who had previously opposed a Bill of Rights, now supported the Bill as a means of silencing the Anti-Federalists' most effective criticism. Many Anti-Federalists, in contrast, now opposed it, realizing the Bill's adoption would greatly lessen the chances of a second constitutional convention, which they desired.{{sfnp|Wood|2009|p=71}} Anti-Federalists such as [[Richard Henry Lee]] also argued that the Bill left the most objectionable portions of the Constitution, such as the federal judiciary and [[direct taxation]], intact.<ref name=Levy />

On November 20, 1789, New Jersey ratified eleven of the twelve amendments, including the Fourth. On December 19, 1789, December 22, 1789, and January 19, 1790, respectively, Maryland, North Carolina, and South Carolina ratified all twelve amendments.{{sfnp|Labunski|2006|p=245}} On January 25 and 28, 1790, respectively, New Hampshire and Delaware ratified eleven of the Bill's twelve amendments, including the Fourth.{{sfnp|Labunski|2006|p=245}} This brought the total of ratifying states to six of the required ten, but the process stalled in other states: Connecticut and Georgia found a Bill of Rights unnecessary and so refused to ratify, while Massachusetts ratified most of the amendments, but failed to send official notice to the Secretary of State that it had done so (all three states would later ratify the Bill of Rights for sesquicentennial celebrations in 1939).<ref name=Levy>{{cite encyclopedia|url=http://www.highbeam.com/doc/1G2-3425000220.html|archive-url=https://web.archive.org/web/20130921061259/http://www.highbeam.com/doc/1G2-3425000220.html|url-status=dead|archive-date=September 21, 2013|title=Bill of Rights (United States)|author=Levy, Leonard W.|year=1986|encyclopedia=Encyclopedia of the American Constitution|publisher=|access-date=July 16, 2013}}</ref>

In February through June 1790, New York, Pennsylvania, and Rhode Island each ratified eleven of the amendments, including the Fourth. Virginia initially postponed its debate, but after Vermont was admitted to the Union in 1791, the total number of states needed for ratification rose to eleven. Vermont ratified on November 3, 1791, approving all twelve amendments, and Virginia finally followed on December 15, 1791.<ref name=Levy /> Secretary of State [[Thomas Jefferson]] announced the adoption of the ten successfully ratified amendments on March 1, 1792.{{sfnp|Labunski|2006|p=255}}

==Applicability==
{{quote box
| quote  = The point of the Fourth Amendment, which often is not grasped by zealous officers, is not that it denies law enforcement the support of the usual inferences which reasonable men draw from evidence. Its protection consists in requiring that those inferences be drawn by a neutral and detached magistrate instead of being judged by the officer engaged in the often competitive enterprise of ferreting out crime. Any assumption that evidence sufficient to support a magistrate's disinterested determination to issue a search warrant will justify the officers in making a search without a warrant would reduce the Amendment to a nullity, and leave the people's homes secure only in the discretion of police officers. Crime, even in the privacy of one's own quarters, is, of course, of grave concern to society, and the law allows such crime to be reached on proper showing. The right of officers to thrust themselves into a home is also a grave concern, not only to the individual, but to a society which chooses to dwell in reasonable security and freedom from surveillance. When the right of privacy must reasonably yield to the right of search is, as a rule, to be decided by a judicial officer, not by a policeman or government enforcement agent.| source =
--[[Supreme Court Justice|Justice]] [[Robert H. Jackson]] in the Opinion of the Court in ''[[Johnson v. United States (1948 Fourth Amendment case)|Johnson v. United States]]'' (1948).<ref>{{cite web |title=Johnson v. United States, 333 U.S. 10 (1948), at 13-14. |url=https://supreme.justia.com/cases/federal/us/333/10/ |publisher=Justia US Supreme Court Center |access-date=July 10, 2023 |date=February 2, 1948}}</ref>| width  = 27%
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The Fourth Amendment, and the personal rights which it secures, have a long history.<ref name="19610306JUSSCC">{{cite web |title=Silverman v. United States, 365 U.S. 505 (1961), at 511. |url=https://supreme.justia.com/cases/federal/us/365/505/ |publisher=Justia US Supreme Court Center |access-date=January 26, 2021 |date=March 6, 1961}}</ref> The Bill of Rights originally restricted only the [[Federal government of the United States|federal government]], and went through a long initial phase of "judicial dormancy;"{{sfnp|Labunski|2006|p=258–59}} in the words of historian [[Gordon S.&nbsp;Wood]], "After ratification, most Americans promptly forgot about the first ten amendments to the Constitution."{{sfnp|Wood|2009|p=72}} Federal jurisdiction regarding criminal law was narrow until the late 19th century when the [[Interstate Commerce Act]] and [[Sherman Antitrust Act]] were passed. As federal criminal jurisdiction expanded to include other areas such as [[narcotic]]s, more questions about the Fourth Amendment came to the [[Supreme Court of the United States|U.S. Supreme Court]].{{sfnp|Lasson|1937|p=106}} In [[Hale v. Henkel]] (1906), the Supreme Court applied the Fourth Amendment to corporations, protecting corporate records from search and seizure.<ref>{{Cite book |last=Blumberg |first=Phillip I. |url=https://www.google.com/books/edition/The_Multinational_Challenge_to_Corporati/-E_KLQAmCtwC?hl=en&gbpv=1&dq=Hale+v+Henkel+4th+amendment+corporation&pg=PA41&printsec=frontcover |title=The Multinational Challenge to Corporation Law: The Search for a New Corporate Personality |date=1993-04-08 |publisher=Oxford University Press |isbn=978-0-19-536134-6 |language=en}}</ref> The Supreme Court responded to these questions by stating on the one hand that the government powers to search and seizure are limited by the Fourth Amendment so that arbitrary and oppressive interference by enforcement officials with the privacy and personal security of individuals are prevented<ref>{{cite web|title=United States v. Martinez-Fuerte, 428 U.S. 543 (1976), at 427|url=https://supreme.justia.com/cases/federal/us/428/543/|publisher=Justia US Supreme Court Center|access-date=August 9, 2020|date=July 6, 1976}}</ref> and by outlining on the other hand the fundamental purpose of the amendment as guaranteeing "the privacy, dignity and security of persons against certain arbitrary and invasive acts by officers of the Government, without regard to whether the government actor is investigating crime or performing another function".<ref name="Ontario v. Quon">''[[Ontario v. Quon]]'', 130 S.Ct. 2619, {{ussc|560|746|2010|docket=08-1332}}.</ref> To protect personal privacy and dignity against unwarranted intrusion by the State is the overriding function of the Fourth Amendment according to the Court in ''[[Schmerber v. California]]'' (1966),<ref>{{cite web|title=Schmerber v. California, 384 U.S. 757 (1966), at 767|url=https://supreme.justia.com/cases/federal/us/384/757/|publisher=Justia US Supreme Court Center|access-date=September 3, 2020|date=June 20, 1966}}</ref> because "[t]he security of one's privacy against arbitrary intrusion by the police" is "at the core of the Fourth Amendment" and "basic to a free society".<ref>{{cite web|title=Wolf v. Colorado, 338 U.S. 25 (1949), at 27|url=https://supreme.justia.com/cases/federal/us/338/25/|publisher=Justia US Supreme Court Center|access-date=September 3, 2020|date=June 27, 1949}}</ref> Pointing to historic precedents like ''[[Entick v Carrington]]'' (1765) and ''[[Boyd v. United States]]'' (1886), the Supreme Court held in ''[[Silverman v. United States]]'' (1961) that the Fourth Amendments core is the right to retreat into his own home and there be free from unreasonable governmental intrusion.<ref name="19610306JUSSCC" /> The Supreme Court declared in ''[[Berger v. New York]]'' (1967) that the Fourth Amendment's protections include "conversation" and is not limited to "persons, houses, papers, and effects".<ref>{{cite web |title=Berger v. New York, 388 U.S. 41 (1967), at 51. |url=https://supreme.justia.com/cases/federal/us/388/41/ |website=Justia US Supreme Court Center |access-date=September 18, 2023 |archive-url=https://web.archive.org/web/20230918144644/https://supreme.justia.com/cases/federal/us/388/41/ |archive-date=September 18, 2023 |date=June 12, 1967}}</ref> The [[New York Court of Appeals]] observed in 1975: "The basic purpose of the constitutional protections against unlawful searches and seizures is to safeguard the privacy and security of each and every person against all arbitrary intrusions by government. Therefore, any time an intrusion on the security and privacy of the individual is undertaken with intent to harass or is based upon mere whim, caprice or idle curiosity, the spirit of the Constitution has been violated and the aggrieved party may invoke the exclusionary rule or appropriate forms of civil redress."<ref>{{cite web |author1=[[New York Court of Appeals]] |title=People v De Bour |url=https://nycourts.gov/reporter/archives/p_debour.htm |website=nycourts.gov |access-date=October 27, 2023 |archive-url=https://web.archive.org/web/20231027201259/https://nycourts.gov/reporter/archives/p_debour.htm |archive-date=October 27, 2023 |date=June 15, 1976}}</ref><ref>{{cite web |title=Close Encounters of the Police Kind |url=https://archive.nysba.org/Sections/Criminal_Justice/Criminal_Justice_PDFs/DeBour_Report_2018.html |website=New York State Bar Association |access-date=18 June 2022 |page=5 |format=PDF|archive-url=https://web.archive.org/web/20231027201027/https://archive.nysba.org/Sections/Criminal_Justice/Criminal_Justice_PDFs/DeBour_Report_2018.html|archive-date=October 27, 2023}}</ref> With a view to ''[[Camara v. Municipal Court of City and County of San Francisco|Camara v. Municipal Court]]'' (1967)<ref>{{cite web|title=Camara v. Municipal Court, 387 U.S. 523 (1967), at 528.|url=https://supreme.justia.com/cases/federal/us/387/523/|publisher=Justia US Supreme Court Center|access-date=April 10, 2021|date=June 5, 1967}}</ref> the Supreme Court observed in ''[[Torres v. Madrid]]'' (2021) that the focus of the Fourth Amendment is the privacy and security of individuals, not the particular manner of arbitrary invasion by governmental officials.<ref>{{cite web|title=''Roxanne Torres v. Janice Madrid, et al.'', Opinion of the Court, Slip Opinion page 9.|url=https://www.supremecourt.gov/opinions/20pdf/19-292_21p3.pdf|publisher=United States Supreme Court|access-date=April 10, 2021|archive-url=https://web.archive.org/web/20210405100014/https://www.supremecourt.gov/opinions/20pdf/19-292_21p3.pdf|archive-date=April 5, 2021|date=March 25, 2021}}</ref>  In ''[[Mapp v. Ohio]]'' (1961),<ref name=Mapp>''[[Mapp v. Ohio]]'', {{ussc|367|643|1961}}.</ref> the Supreme Court ruled that the Fourth Amendment [[Incorporation of the Bill of Rights|applies to the states]] by way of the [[Due Process Clause]] of the [[Fourteenth Amendment to the United States Constitution|Fourteenth Amendment]].<ref>{{cite encyclopedia|url=http://www.highbeam.com/doc/1G2-3425001584.html|archive-url=https://web.archive.org/web/20130921061252/http://www.highbeam.com/doc/1G2-3425001584.html|url-status=dead|archive-date=September 21, 2013|title=''Mapp v. Ohio''|author=Landynski, Jacob W.|year=1986|encyclopedia=Encyclopedia of the American Constitution|publisher=|access-date=July 28, 2013}}</ref>

{{quote box
| quote  = The effect of the Fourth Amendment is to put the courts of the United States and Federal officials, in the exercise of their power and authority, under limitations and restraints as to the exercise of such power and authority, and to forever secure the people, their persons, houses, papers, and effects, against all unreasonable searches and seizures under the guise of law. This protection reaches all alike, whether accused of crime or not, and the duty of giving to it force and effect is obligatory upon all intrusted under our Federal system with the enforcement of the laws. The tendency of those who execute the criminal laws of the country to obtain conviction by means of unlawful seizures and enforced confessions, the latter often obtained after subjecting accused persons to unwarranted practices destructive of rights secured by the Federal Constitution, should find no sanction in the judgments of the courts, which are charged at all times with the support of the Constitution, and to which people of all conditions have a right to appeal for the maintenance of such fundamental rights.| source =
--[[Supreme Court Justice|Justice]] [[William R. Day]] in the Opinion of the Court in ''[[Weeks v. United States]]'' (1914).<ref>{{cite web |title=Weeks v. United States, 232 U.S. 383 (1914), at 391-392. |url=https://supreme.justia.com/cases/federal/us/232/383/ |publisher=Justia US Supreme Court Center |access-date=January 18, 2021 |date=February 24, 1914}}</ref>| width  = 27%
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Fourth Amendment case law deals with three central issues: what government activities constitute "search" and "seizure;" what constitutes [[probable cause]] for these actions; how violations of Fourth Amendment rights should be addressed.<ref name=Arenella>{{cite encyclopedia|url=http://www.highbeam.com/doc/1G2-3425001005.html|archive-url=https://web.archive.org/web/20130921061331/http://www.highbeam.com/doc/1G2-3425001005.html|url-status=dead|archive-date=September 21, 2013|title=Fourth Amendment|author=Arenella, Peter|year=1992|encyclopedia=Encyclopedia of the American Constitution|publisher=|access-date=July 28, 2013}}</ref> The text of the amendment is brief, and most of the law determining what constitutes an unlawful search and seizure is found in court rulings. The brief definitions of the terms "search" and "seizure" was concisely summarized in ''[[United States v. Jacobsen]]'', which said that the Fourth Amendment:

{{blockquote|protects two types of expectations, one involving "searches", the other "seizures".  A ''search'' occurs when an expectation of privacy that society is prepared to consider reasonable is infringed.  A ''seizure'' of property occurs where there is some meaningful interference with an individual's possessory interests in that property.<ref>''Jacobson v. United States'', {{ussc|466|109|1984|pin=113}}</ref>}}

"The Fourth Amendment search and seizure doctrine involves a complex compromise between public safety and the constitutional right to personal liberty."<ref>{{Cite journal|last=Pedro|first=Portia|date=2008-04-01|title=Recent Case, Ninth Circuit Considers Community's Racial Tension with Police in Finding Illegal Seizure and Lack of Voluntary Consent. — United States V. Washington, 490 F.3d 765 (9th Cir. 2007)|url=https://scholarship.law.bu.edu/faculty_scholarship/337|journal=Harvard Law Review|volume=121|issue=6|pages=1669}}</ref>'''{{rp|1669}}''' The Fourth Amendment typically requires "a neutral and detached authority interposed between the police and the public", and it is offended by "general warrants" and laws that allow searches to be conducted "indiscriminately and without regard to their connection with [a] crime under investigation",<ref>''[[Berger v. New York]]'', {{Ussc|388|41|1967|pin=54,59}}.</ref> for the "basic purpose of the Fourth Amendment, which is enforceable against the States through the Fourteenth, through its prohibition of 'unreasonable' searches and seizures is to safeguard the privacy and security of individuals against arbitrary invasions by governmental officials".<ref>''[[Camara v. Municipal Court of City and County of San Francisco]]'', {{ussc|387|523|1967}}.</ref>

The Fourth Amendment has been held to mean that a search or an arrest generally requires a judicially sanctioned [[Warrant (law)|warrant]], because the basic rule under the Fourth Amendment is that arrests and "searches conducted outside the judicial process, without prior approval by judge or magistrate, are ''per se'' unreasonable under the Fourth Amendment—subject only to a few specifically established and well-delineated exceptions".<ref>''[[Coolidge v. New Hampshire]]'', {{ussc|403|443|1971}}, at page 454–454, quoting [[Katz v. United States]], {{ussc|389|347|1967}} at page 357.</ref><ref>''[[Arizona v. Gant]]'', {{ussc|556|332|2009}}, at page 338.</ref> In order for such a warrant to be considered reasonable, it must be supported by probable cause and be limited in scope according to specific information supplied by a person (usually a law enforcement officer) who has [[Affidavit|sworn by it]] and is therefore [[Perjury|accountable to the issuing court]]. Where there was no clear practice, either approving or disapproving the type of search at issue, at the time the constitutional provision was enacted, the "reasonableness" of a search is judged by balancing the intrusion on the individual's Fourth Amendment interests against the promotion of legitimate governmental interests.<ref>''[[Vernonia School District 47J v. Acton]]'', {{ussc|515|646|1995}}, at 652-653.</ref> The Supreme Court further held in ''[[Chandler v. Miller]]'' (1997): "To be reasonable under the Fourth Amendment, a search ordinarily must be based on individualized suspicion of wrongdoing. But particularized exceptions to the main rule are sometimes warranted based on 'special needs, beyond the normal need for law enforcement'.&nbsp;... When such 'special needs' are alleged, courts must undertake a context-specific inquiry, examining closely the competing private and public interests advanced by the parties."<ref>''[[Chandler v. Miller]]'', {{ussc|520|305|1997}}, at 313-314.</ref> The reasonableness of any particular search and seizure according to the Supreme Court in ''[[Terry v. Ohio]]'' (1968) must be assessed in light of the particular circumstances against the standard of whether a man of reasonable caution is warranted in believing that the action taken was appropriate.<ref>{{cite web |title=Terry v. Ohio, 392 U.S. 1 (1968), at 21-22. |url=https://supreme.justia.com/cases/federal/us/392/1/ |publisher=Justia US Supreme Court Center |access-date=October 27, 2023 |archive-url=https://web.archive.org/web/20231027195901/https://supreme.justia.com/cases/federal/us/392/1/ |archive-date=October 27, 2023 |date=June 10, 1968}}</ref> The amendment applies to governmental searches and seizures, but not those done by private citizens or organizations who are not acting on behalf of a government.<ref>''[[United States v. Jacobsen]]'', {{ussc|466|109|1984}}: "This Court has&nbsp;... consistently construed this protection as proscribing only governmental action; it is wholly inapplicable to a search or seizure, even an unreasonable one, effected by a private individual not acting as an agent of the Government or with the participation or knowledge of any governmental official." (punctuation omitted).</ref> In ''[[Ontario v. Quon]]'' (2010), the Court applied the amendment to a municipal government in its capacity as an employer, ruling that the City of Ontario had not violated the Fourth Amendment rights of city police officers by obtaining from the communications company and reviewing transcripts of text messages sent using government-provided pagers.<ref name="Ontario v. Quon"/><ref>{{cite web|url=http://www.scotusblog.com/case-files/cases/city-of-ontario-v-quon/|title=''City of Ontario v. Quon''|publisher=[[SCOTUSblog]]|access-date=December 28, 2013}}</ref>

===Search===

[[File:US Supreme Court Justice Potter Stewart - 1976 official portrait.jpg|thumb|[[Potter Stewart]] wrote the majority decision in ''[[Katz v. United States]]'', which expanded Fourth Amendment protections to electronic surveillance.]]

One threshold question in the Fourth Amendment jurisprudence is whether a "search" has occurred. Initial Fourth Amendment case law hinged on a citizen's [[property rights]]—that is, when the government physically intrudes on "persons, houses, papers, or effects" for the purpose of obtaining information, a "search" within the original meaning of the Fourth Amendment, has occurred. Early 20th-century Court decisions, such as ''[[Olmstead v. United States]]'' (1928), held that Fourth Amendment rights applied in cases of physical intrusion, but not to other forms of police surveillance (e.g., wiretaps).<ref name="Katz">{{cite encyclopedia|url=http://www.highbeam.com/doc/1G2-3425001430.html|archive-url=https://web.archive.org/web/20130921061449/http://www.highbeam.com/doc/1G2-3425001430.html|url-status=dead|archive-date=September 21, 2013|title=''Katz v. United States'' 389 U.S. 347 (1967)|author=Schwartz, Herman|year=1986|encyclopedia=Encyclopedia of the American Constitution|publisher=|access-date=July 28, 2013}}</ref> In ''[[Silverman v. United States]]'' (1961), the Court stated of the amendment that "at the very core stands the right of a man to retreat into his own home and there be free from unreasonable governmental intrusion".<ref>''[[Silverman v. United States]]'', {{ussc|365|505|1961|pin=511}}.</ref>

Fourth Amendment protections expanded significantly with ''[[Katz v. United States]]'' (1967).<ref name=Katz /><ref>''[[Katz v. United States]]'', {{ussc|389|347|1967}}.</ref> In ''Katz'', the Supreme Court expanded that focus to embrace an individual's [[right to privacy]], and ruled that a search had occurred when the government wiretapped a [[telephone booth]] using a microphone attached to the outside of the glass. While there was no physical intrusion into the booth, the Court reasoned that: 1) Katz, by entering the booth and shutting the door behind him, had exhibited his expectation that "the words he utters into the mouthpiece will not be broadcast to the world"; and 2) society believes that his expectation was [[Reasonable person|reasonable]]. Justice [[Potter Stewart]] wrote in the majority opinion that "the Fourth Amendment protects people, not places".<ref>''Katz'', 389 U.S. at 351.</ref> A "search" occurs for purposes of the Fourth Amendment when the government violates a person's "reasonable expectation of privacy".<ref>''Katz'', 389 U.S. at 351; at 360-61 (Harlan, J., concurring)</ref> Katz's reasonable [[expectation of privacy]] thus provided the basis to rule that the government's intrusion, though electronic rather than physical, was a search covered by the Fourth Amendment, and thus necessitated a warrant.<ref name=Katz /><ref name=Lure>{{cite book|last=Schroeder|first=Steve|title=The Lure: The True Story of How the Department of Justice Brought Down Two of the World's Most Dangerous Cyber Criminals|url=https://archive.org/details/luretruestoryofh0000schr|url-access=registration|year=2012|publisher=Cengage Learning|isbn=978-1-4354-5713-3|page=[https://archive.org/details/luretruestoryofh0000schr/page/127 127]}}</ref> The Court said it was not recognizing any general right to privacy in the Fourth Amendment,<ref>Morgan, Candace. "[https://books.google.com/books?id=HV8hITArW9MC&pg=PA41 Challenges and Issues Today]" in ''Intellectual Freedom Manual'', pp.&nbsp;41–42 (American Library Association, Office for Intellectual Freedom, 2010).</ref> and that this wiretap could have been authorized if proper procedures had been followed.<ref name=Lure />

This decision in ''Katz'' was later developed into the now commonly used two-prong test, adopted in ''[[Smith v. Maryland]]'' (1979),<ref name="Smith v. Maryland">''[[Smith v. Maryland]]'', {{ussc|442|735|1979}}.</ref> for determining whether a search has occurred for purposes of the Fourth Amendment:<ref>{{cite journal|url=http://stlr.stanford.edu/pdf/freiwald-first-principles.pdf|title=First Principles of Communications Privacy|first=Susan|last=Freiwald|journal=Stanford Technology Law Review|year=2007|issue=3|url-status=dead|archive-url=https://web.archive.org/web/20130617132308/http://stlr.stanford.edu/pdf/freiwald-first-principles.pdf|archive-date=June 17, 2013}}</ref><ref>Sorosky, Schuyler. "[http://digitalcommons.lmu.edu/cgi/viewcontent.cgi?article=2630&context=llr United States v. Forrester: An Unwarranted Narrowing of the Fourth Amendment]", ''Loyola of Los Angeles Law Review'', Vol.&nbsp;41, p.&nbsp;1121, 1126 (2008).</ref>
# a person "has exhibited an actual (subjective) expectation of privacy"; and
# society is prepared to recognize that this expectation is (objectively) reasonable.

The Supreme Court has held that the Fourth Amendment does not apply to information that is voluntarily shared with third parties.<ref>''Smith v. Maryland'', 442 U.S. 735, 743-44 (1979); ''United States v. Miller'', 425 U.S. 435, 440-41 (1976).</ref><ref>{{cite web|title=''Smith v. Maryland''|url=https://www.oyez.org/cases/1970-1979/1978/1978_78_5374/|work=The Oyez Project at IIT Chicago-Kent College of Law|access-date=January 13, 2014|quote=Because the Fourth Amendment does not apply to information that is voluntarily given to third parties, the telephone numbers that are regularly and voluntarily provided to telephone companies by their customers do not gain Fourth Amendment protections.}}</ref> In ''Smith'', the Court held individuals have no "legitimate expectation of privacy" regarding the telephone numbers they dial because they knowingly give that information to telephone companies when they dial a number.<ref name="Smith v. Maryland"/><ref>''Smith'', 442 U.S. at 742.</ref> However, under ''[[Carpenter v. United States]]'' (2018), individuals have a reasonable expectation of privacy under the Fourth Amendment regarding cell phone records even though they themselves turned over that information to "third parties" (i.e. the cell phone companies). Prior to the Carpenter ruling, law enforcement was able to retrieve cell site location information (CSLI) that included where a cell phone user had traveled over many months and with which other cell phone users they had associated. Carpenter v. United States serves as a landmark case because it slightly narrowed the Third Party Doctrine, thus requiring law enforcement to first obtain a search warrant before receiving CSLI records.<ref>{{cite web|url=http://www.scotusblog.com/2018/06/opinion-analysis-court-holds-that-police-will-generally-need-a-warrant-for-cellphone-location-information/|title=Opinion analysis: Court holds that police will generally need a warrant for cellphone location information|last=Howe|first=Amy|date=June 22, 2018|publisher=[[SCOTUSblog]]|access-date=June 22, 2018}}</ref> "In the 5-4 [Carpenter] decision, the Court ruled 'narrowly' in favor of privacy, finding the government had constitutionally violated Mr. Carpenter's reasonable expectation of privacy by acquiring this private information without a warrant."

Following ''Katz'', the vast majority of Fourth Amendment search cases have turned on the right to privacy, but in ''[[United States v. Jones (2012)|United States v. Jones]]'' (2012), the Court ruled that the ''Katz'' standard did not replace earlier case law, but rather, has supplemented it.<ref name=Jones2012>''[[United States v. Jones (2012)|United States v. Jones]]'', {{ussc|565||2012|docket=10-1259}}.</ref> In ''Jones'', law enforcement officers had attached a [[Global Positioning System|GPS]] device on a car's exterior without Jones' knowledge or consent. The Court concluded that Jones was a [[Bailment|bailee]] to the car, and so had a property interest in the car.<ref>{{cite web|url=http://www.scotusblog.com/2012/01/opinion-recap-tight-limit-on-police-gps-use/|title=Opinion recap: Tight limit on police GPS use|last=Denniston|first=Lyle|date=January 23, 2012|publisher=[[SCOTUSblog]]|access-date=January 23, 2012}}</ref> Therefore, since the intrusion on the vehicle—a common law [[trespass]]—was for the purpose of obtaining information, the Court ruled that it was a search under the Fourth Amendment. The Court used similar "trespass" reasoning in ''[[Florida v. Jardines]]'' (2013), to rule that bringing a drug [[detection dog]] to sniff at the front door of a home was a search.<ref name=Jardines>''[[Florida v. Jardines]]'', {{ussc|569||2013|docket=11-564}}.</ref>

In many situations, law enforcement may perform a search when they have a reasonable suspicion of criminal activity, even if it falls short of probable cause necessary for an arrest. Under ''[[Terry v. Ohio]]'' (1968), law enforcement officers are permitted to conduct a limited warrantless search on a level of suspicion less than probable cause under certain circumstances. In ''Terry'', the Supreme Court ruled that when a police officer witnesses "unusual conduct" that leads the officer to reasonably believe "that criminal activity may be afoot", that the suspicious person has a weapon ''and'' that the person is presently dangerous to the officer or others, the officer may conduct a pat-down search ("frisk" the person) to determine whether the person is carrying a weapon.<ref>''[[Terry v. Ohio]]'', {{ussc|392|1|1968}}</ref> This detention and search is known as a [[Terry stop|''Terry'' stop]]. To conduct a frisk, officers must be able to point to specific and articulable facts which, taken together with rational inferences from those facts, reasonably warrant their actions.<ref>{{cite encyclopedia|url=http://www.highbeam.com/doc/1G2-3425002506.html|archive-url=https://web.archive.org/web/20140610085727/http://www.highbeam.com/doc/1G2-3425002506.html|url-status=dead|archive-date=June 10, 2014|title=Terry v. Ohio 392 U.S. 1 (1968) Sibron v. New York 392 U.S. 40 (1968)|author=Landynski, Jacob W.|year=1986|encyclopedia=Encyclopedia of the American Constitution|publisher=|access-date=July 28, 2013}}</ref> As established in ''[[Florida v. Royer]]'' (1983), such a search must be temporary, and questioning must be limited to the purpose of the stop (e.g., officers who stop a person because they have reasonable suspicion to believe the person was driving a stolen car, cannot, after confirming it is not stolen, compel the person to answer questions about anything else, such as contraband).<ref name=Royer>''[[Florida v. Royer]]'', {{ussc|460|491|1983|pin=497–98}}.</ref><ref name=Royer2>{{cite web|url=http://www.casebriefs.com/blog/law/criminal-procedure/criminal-procedure-keyed-to-israel/arrest-search-and-seizure/florida-v-royer/2/|title=Florida v. Royer|publisher=casebriefs.com|access-date=July 28, 2013}}</ref>

===Seizure===

The Fourth Amendment also protects "[t]he right of the people to be secure in their persons, houses, papers and effects, against unreasonable&nbsp;... seizures". A seizure of property occurs when there is "some meaningful interference with an individual's possessory interests in that property",<ref>''Jacobsen'', 466 U.S. at 113.</ref> such as when police officers take personal property away from an owner to use as evidence, or when they participate in an eviction.<ref>''[[Soldal v. Cook County]]'', {{ussc|506|56|1992|pin=61}}. "The right against unreasonable seizures would be no less transgressed if the seizure of the house was undertaken to collect evidence, verify compliance with a housing regulation, effect an eviction by the police, or on a whim, for no reason at all."</ref> The amendment also protects against unreasonable seizure of persons, including a [[Detention (imprisonment)|brief detention]].<ref name="United States v. Mendenhall"/>

A seizure does not occur just because the government questions an individual in a public place. The exclusionary rule would not bar voluntary answers to such questions from being offered into evidence in a subsequent criminal prosecution. The person is not being seized if his freedom of movement is not restrained.<ref name=Royer /><ref>''[[Dunaway v. New York]]'', 442 U.S. 200, 210 n. 12, 99 S.Ct. 2248, 2255 n. 12, 60 L.Ed.2d 824 (1979).</ref> The government may not detain an individual even momentarily without reasonable, objective grounds, with few exceptions. His refusal to listen or answer does not by itself furnish such grounds.<ref name="United States v. Mendenhall"/>

In ''[[United States v. Mendenhall]]'' (1980), the Court held that a person is seized only when, by means of physical force ''or'' show of authority, his freedom of movement is restrained and, in the circumstances surrounding the incident, a reasonable person would believe he was not free to leave.<ref name="United States v. Mendenhall">''[[United States v. Mendenhall]]'', {{ussc|446|544|1980}}.</ref> Under ''[[Torres v. Madrid]]'' (2021), a person is considered to be seized following the use of physical force with the intent to restrain, even if the person manages to escape. In ''[[Florida v. Bostick]]'' (1991), the Court ruled that as long as the police do not convey a message that compliance with their requests is required, the police contact is a "citizen encounter" that falls outside the protections of the Fourth Amendment.<ref>''[[Florida v. Bostick]]'', {{ussc|501|429|1991|pin=439}}.</ref> If a person remains free to disregard questioning by the government, there has been no seizure and therefore no intrusion upon the person's privacy under the Fourth Amendment.<ref name="United States v. Mendenhall"/>

When a person is arrested and taken into police custody, he has been seized (i.e., a reasonable person who is handcuffed and placed in the back of a police car would not think they were free to leave). A person subjected to a routine [[traffic stop]] on the other hand, has been seized, but is not "arrested" because traffic stops are a relatively brief encounter and are more analogous to a [[Terry stop|''Terry'' stop]] than to a formal arrest.<ref name="Knowles v. Iowa">''[[Knowles v. Iowa]]'', {{ussc|525|113|1998|pin=117}}.</ref> If a person is not under suspicion of illegal behavior, a law enforcement official is not allowed to place an individual under arrest simply because this person does not wish to state his identity, provided specific state regulations do not specify this to be the case.<ref>{{cite news|last=Moritz|first=Rob|title=Fed appeals court says refusal to identify no cause for arrest|url=http://www.arkansasnews.com/archive/2008/04/05/News/345838.html|archive-url=https://web.archive.org/web/20080613195115/http://www.arkansasnews.com/archive/2008/04/05/News/345838.html|archive-date=June 13, 2008|access-date=April 6, 2012|newspaper=Arkansas News Bureau|date=April 5, 2008}}</ref> A search incidental to an arrest that is not permissible under state law does not violate the Fourth Amendment, so long as the arresting officer has probable cause.<ref>''[[Virginia v. Moore]]'', {{ussc|553|164|2008|docket=06-1082}}.</ref><ref>{{cite news|url=https://www.usatoday.com/news/washington/judicial/2008-04-23-scotus-search_N.htm|title=Court allows search and seizure in Va. case|work=[[USA Today]]|date=April 23, 2008|access-date=April 11, 2012}}</ref> In ''[[Maryland v. King]]'' (2013), the Court upheld the constitutionality of police swabbing for [[Genetic testing|DNA]] upon arrests for serious crimes, along the same reasoning that allows police to take fingerprints or photographs of those they arrest and detain.<ref>''[[Maryland v. King]]'', {{ussc|569||2013|docket=12-207}}.</ref><ref>June, Daniel. (June 3, 2013)[http://www.jdjournal.com/2013/06/03/supreme-court-approves-use-of-dna-swabbing-in-serious-arrests/ "Supreme Court Approves Use of DNA Swabbing in Serious Arrests"]. ''JDJournal''. Accessed August 2, 2013.</ref>

====Exceptions====

The government may not detain an individual even momentarily without reasonable and articulable suspicion, with a few exceptions. In ''[[Delaware v. Prouse]]'' (1979), the Court ruled an officer has made an illegal seizure when he stops an automobile and detains the driver in order to check his driver's license and the registration of the automobile, because the officer does not have articulable and reasonable suspicion that a motorist is unlicensed or that an automobile is not registered, or either the vehicle or an occupant is otherwise subject to seizure for violation of law.<ref>''[[Delaware v. Prouse]]'', {{ussc|440|648|1979}}.</ref><ref>{{cite encyclopedia|url=http://www.highbeam.com/doc/1G2-3425000155.html|archive-url=https://web.archive.org/web/20140610085710/http://www.highbeam.com/doc/1G2-3425000155.html|url-status=dead|archive-date=June 10, 2014|title=Automobile search|author=Landynski, Jacob W.|year=1986|encyclopedia=Encyclopedia of the American Constitution|publisher=|access-date=July 28, 2013}}</ref>

Where society's need is great, no other effective means of meeting the need is available, and intrusion on people's privacy is minimal, certain discretionless checkpoints toward that end may briefly detain motorists. In ''[[United States v. Martinez-Fuerte]]'' (1976), the Supreme Court allowed discretionless immigration checkpoints.<ref>''[[United States v. Martinez-Fuerte]]'', {{ussc|428|543|1976}}.</ref> In ''[[Michigan Dept. of State Police v. Sitz]]'' (1990), the Supreme Court allowed discretionless sobriety checkpoints.<ref>''[[Michigan Dept. of State Police v. Sitz]]'' {{ussc|496|444|1990}}.</ref> In ''[[Illinois v. Lidster]]'' (2004), the Supreme Court allowed focused informational checkpoints.<ref>''[[Illinois v. Lidster]]'', {{ussc|source=f|540|419|2004}}.</ref> However, in ''[[City of Indianapolis v. Edmond]]'' (2000), the Supreme Court ruled that discretionary checkpoints or general crime-fighting checkpoints are not allowed.<ref>''[[City of Indianapolis v. Edmond]]'', {{ussc|531|32|2000}}.</ref>

===Warrant===

Under the Fourth Amendment, law enforcement must receive written permission from a court of law, or otherwise qualified [[magistrate]], to lawfully search and seize evidence while investigating criminal activity. A court grants permission by issuing a [[writ]] known as a warrant. A search or seizure is generally unreasonable and unconstitutional if conducted without a valid warrant<ref>''[[Maryland v. Dyson]]'', {{ussc|527|465|1999}}.</ref> and the police must obtain a warrant whenever practicable.<ref>{{Cite court|litigants=Andrews v. Fuoss|vol=417|reporter=F.3d|opinion=813|pinpoint=819|court=8th Cir.|date=2005|url=https://scholar.google.com/scholar_case?hl=en&as_sdt=40000006&case=2225498566309744665&scilh=0|access-date=February 12, 2014}}</ref> Searches and seizures without a warrant are not considered unreasonable if one of the specifically established and well-delineated exceptions to the warrant requirement applies.<ref name=Katz/><ref>''Flippo v. West Virginia'', {{ussc|528|11|1999}}; ''[[California v. Acevedo]]'', {{ussc|500|565|1991}}.</ref><ref name=TLO>''[[New Jersey v. T. L. O.]]'', ''{{ussc|469|325|1985}}''. "[W]arrantless searches are per se unreasonable, subject only to a few specifically delineated and well-recognized exceptions.&nbsp;... full-scale searches—whether conducted in accordance with the warrant requirement or pursuant to one of its exceptions—are 'reasonable' in Fourth Amendment terms only on a showing of probable cause to believe that a crime has been committed and that evidence of the crime will be found in the place to be searched."</ref> These exceptions apply "[o]nly in those exceptional circumstances in which special needs, beyond the normal need for law enforcement, make the warrant and probable cause requirement impracticable".<ref>''T. L. O.'', 469 U.S., [[Harry Blackmun|Blackmun, J.]], concurring.</ref> In [[Marshall v. Barlow's, Inc.]], the Supreme Court ruled that [[OSHA]] needed probable cause to inspect a business.<ref>{{Cite book |last=Resources |first=United States Congress Senate Committee on Labor and Human |url=https://www.google.com/books/edition/Oversight_of_the_Occupational_Safety_and/jC7lym3iA0wC?hl=en&gbpv=1&dq=%22Marshall+v.+Barlow%E2%80%99s+Inc.%22+OSHA&pg=PA738&printsec=frontcover |title=Oversight of the Occupational Safety and Health Administration: Hearings Before the Committee on Labor and Human Resources, United States Senate, One Hundredth Congress, Second Session ... April 18, 19, and 20, 1988 |date=1988 |publisher=U.S. Government Printing Office |language=en}}</ref>

In these situations where the warrant requirement doesn't apply a search or seizure nonetheless must be justified by some individualized suspicion of wrongdoing.<ref>{{cite journal|last=Keeley III.|first=Charles J.|title=Article 8 – Subway Searches: Which Exception to the Warrant and Probable Cause Requirements Applies to Suspicionless Searches of Mass Transit Passengers To Prevent Terrorism?|journal=Fordham Law Review|year=2006|volume=74|issue=6|page=3236|access-date=December 28, 2013|url=http://ir.lawnet.fordham.edu/cgi/viewcontent.cgi?article=4178&context=flr}}</ref> However, the U.S. Supreme Court carved out an exception to the requirement of individualized suspicion. It ruled that, "In limited circumstances, where the privacy interests implicated by the search are minimal and where an important governmental interest furthered by the intrusion would be placed in jeopardy by a requirement of individualized suspicion" a search [or seizure] would still be reasonable.<ref>''[[Skinner v. Railway Labor Executives Association]]'', {{ussc|489|602|1989}}, at 624.</ref>

===Probable cause===

{{main|Probable cause}}

The Supreme Court in ''[[Berger v. New York]]'' (1967) explained that the purpose of the probable cause requirement of the Fourth Amendment is to keep the state out of constitutionally protected areas until it has reason to believe that a specific crime has been or is being committed.<ref>{{cite web |title=Berger v. New York, 388 U.S. 41 (1967), at 59.|url=https://supreme.justia.com/cases/federal/us/388/41/ |website=Justia US Supreme Court Center |access-date=September 18, 2023 |archive-url=https://web.archive.org/web/20230918144644/https://supreme.justia.com/cases/federal/us/388/41/ |archive-date=September 18, 2023 |date=June 12, 1967}}</ref> The standards of probable cause<ref>{{cite web|author=Senior Specialist Charles Doyle|title=CSR Memorandum to the United Senate Select Committee on Intelligence entitled "Probable Cause, Reasonable Suspicion, and Reasonableness Standards in the Context of the Fourth Amendment and the Foreign Intelligence Act"|url=https://fas.org/sgp/crs/intel/m013006.pdf|publisher=Congressional Research Service via the [[Federation of American Scientists]]|access-date=September 27, 2019|archive-url=https://web.archive.org/web/20190824161409/https://fas.org/sgp/crs/intel/m013006.pdf|archive-date=August 24, 2019|date=January 30, 2006}}</ref> differ for an arrest and a search. The government has probable cause to make an arrest when "the facts and circumstances within their knowledge and of which they had reasonably trustworthy information" would lead a prudent person to believe the arrested person had committed or was committing a crime.<ref>''[[Beck v. Ohio]]'', {{ussc|379|89|1964|pin=91}}.</ref> Probable cause to arrest must exist before the arrest is made. Evidence obtained after the arrest may not apply retroactively to justify the arrest.<ref>''[[Johnson v. United States (1948 Fourth Amendment case)|Johnson v. United States]]'', {{ussc|333|10|1948}}.</ref>

When police conduct a search, the amendment requires that the warrant establish probable cause to believe the search will uncover criminal activity or contraband. They must have legally sufficient reasons to believe a search is necessary. In ''[[Carroll v. United States]]'' (1925), the Supreme Court stated that probable cause to search is a flexible, common-sense standard.<ref name=Carroll>''[[Carroll v. United States]]'', {{ussc|267|132|1925}}.</ref><ref>{{cite encyclopedia|url=http://www.highbeam.com/doc/1G2-3425000387.html|archive-url=https://web.archive.org/web/20140610085725/http://www.highbeam.com/doc/1G2-3425000387.html|url-status=dead|archive-date=June 10, 2014|title=''Carroll v. United States'' 267 U.S. 132 (1925)|author=Landynski, Jacob W.|year=1986|encyclopedia=Encyclopedia of the American Constitution|publisher=|access-date=July 28, 2013}}</ref> To that end, the Court ruled in ''[[Dumbra v. United States]]'' (1925) that the term probable cause means "less than evidence that would justify condemnation",<ref>''[[Dumbra v. United States]]'', {{ussc|268|435|1925}}.</ref> reiterating ''Carroll''{{'}}s assertion that it merely requires that the facts available to the officer would "warrant a man of reasonable caution" in the belief that specific items may be contraband or stolen property or useful as evidence of a crime.<ref>''Carroll'', 267 U.S. at 162.</ref> It does not demand any showing that such a belief be correct or more likely true than false. A "practical, non-technical" probability that incriminating evidence is involved is all that is required.<ref>''[[Texas v. Brown]]'', {{ussc|460|730|1983|pin=742}}.</ref> In ''[[Illinois v. Gates]]'' (1983), the Court ruled that the reliability of an informant is to be determined based on the "[[totality of the circumstances]]".<ref>''[[Illinois v. Gates]]'', {{ussc|462|213|1983}}.</ref>

==Exceptions to the warrant requirement==
===Consent===

{{main|Consent search}}

If a [[Party (law)|party]] gives consent to a search, a warrant is not required. There are exceptions and complications to the rule, including the scope of the consent given, whether the consent is voluntarily given, and whether an individual has the right to consent to a search of another's property.<ref>Holcomb, J. W. (March 2003).[http://www2.fbi.gov/publications/leb/2003/mar03leb.pdf Obtaining Written Consent to Search]. ''FBI Law Enforcement Bulletin''</ref> In ''[[Schneckloth v. Bustamonte]]'' (1973), the Court ruled that a consent search is still valid even if the police do not inform a suspect of his right to refuse the search.<ref>''[[Schneckloth v. Bustamonte]]'', {{ussc|412|218|1973}}.</ref> This contrasts with [[Fifth Amendment to the United States Constitution|Fifth Amendment rights]], which cannot be relinquished without an explicit [[Miranda warning|''Miranda'' warning]] from police.<ref>{{cite encyclopedia |url=http://www.highbeam.com/doc/1G2-3425002231.html |archive-url=https://web.archive.org/web/20140610085723/http://www.highbeam.com/doc/1G2-3425002231.html |url-status=dead |archive-date=June 10, 2014 |title=''Schneckloth v. Bustamonte'' 412 U.S. 218 (1973) |author=Landynski, Jacob W. |year=1986 |encyclopedia=Encyclopedia of the American Constitution |publisher= |access-date=July 31, 2013}}</ref>

The Court stated in ''[[United States v. Matlock]]'' (1974) that a third party co-occupant could give consent for a search without violating a suspect's Fourth Amendment rights.<ref>''[[United States v. Matlock]]'', {{ussc|415|164|1974}}.</ref><ref name=Crawford /> However, in ''[[Georgia v. Randolph]]'' (2006), the Supreme Court ruled that when two co-occupants are both present, one consenting and the other rejecting the search of a shared residence, the police may not make a search of that residence within the consent exception to the warrant requirement.<ref>''Georgia v. Randolph'', {{ussc|547|103|2006}}.</ref> Per the Court's ruling in ''[[Illinois v. Rodriguez]]'' (1990),<ref>''[[Illinois v. Rodriguez]]'', {{ussc|497|177|1990}}.</ref> a consent search is still considered valid if police accept in good faith the consent of an "apparent authority", even if that party is later discovered to not have authority over the property in question.<ref name=Crawford>{{cite web|url=https://www.questia.com/read/1G1-18701410 |title=Consent searches: guidelines for officers|author=Crawford, Kimberly A.|date=August 1, 1996|work=The FBI Law Enforcement Bulletin|via=|url-access=|access-date=}}{{dead link|date=July 2021}}</ref> A telling case on this subject is ''Stoner v. California'', in which the Court held that police officers could not rely in good faith upon the apparent authority of a hotel clerk to consent to the search of a guest's room.<ref>''Stoner v. California'', {{ussc|376|483|1969}}.</ref>

===Plain view and open fields===

{{main|Plain view doctrine|Open-fields doctrine}}

According to the plain view doctrine as defined in ''[[Coolidge v. New Hampshire]]'' (1971),<ref>''[[Coolidge v. New Hampshire]]'', {{ussc|403|443|1971}}.</ref> if an officer is lawfully present, he may seize objects that are in "plain view". However, the officer must have had probable cause to believe the objects are contraband,<ref>{{cite encyclopedia|url=http://www.highbeam.com/doc/1G2-3425001924.html|archive-url=https://web.archive.org/web/20140610085718/http://www.highbeam.com/doc/1G2-3425001924.html|url-status=dead|archive-date=June 10, 2014|title=Plain View Doctrine|author=Landynski, Jacob W.|year=1986|encyclopedia=Encyclopedia of the American Constitution|publisher=|access-date=July 31, 2013}}</ref> and the criminality of the object in plain view must be obvious by its very nature. In ''[[Arizona v. Hicks]]'', the Supreme Court held that an officer stepped beyond the plain view doctrine when he moved a turntable in order to view its serial number to confirm that the turntable was stolen.<ref>''Arizona v. Hicks'', 480 U.S. 321 (1987).</ref> "A search is a search," proclaimed the Court, "even if it happens to disclose nothing but the bottom of a turntable."<ref>480 U.S. 321, 325 (1987).</ref>

Similarly, "open fields" such as pastures, open water, and woods may be searched without a warrant, on the ground that conduct occurring therein would have no reasonable expectation of privacy. The doctrine was first articulated by the Court in ''[[Hester v. United States]]'' (1924), which stated that "the special protection accorded by the Fourth Amendment to the people in their 'persons, houses, papers, and effects' is not extended to the open fields".<ref>''[[Hester v. United States]]'', {{ussc|265|57|1924}}.</ref>

In ''[[Oliver v. United States]]'' (1984),<ref>''[[Oliver v. United States]]'', {{ussc|466|170|1984}}.</ref> the police ignored a "no trespassing" sign and a fence, trespassed onto the suspect's land without a warrant, followed a path for hundreds of feet, and discovered a field of marijuana. The Supreme Court ruled that no search had taken place, because there was no privacy expectation regarding an open field:
{{blockquote|open fields do not provide the setting for those intimate activities that the Amendment is intended to shelter from government interference or surveillance. There is no societal interest in protecting the privacy of those activities, such as the cultivation of crops, that occur in open fields.<ref>''Oliver'', 466 U.S. at 179.</ref>}}

According to a 2024 study, at least 96% of all private land in the country, about 1.2 billion acres, qualify as unprotected open fields under current Fourth Amendment law.<ref>{{Cite web |title=Good Fences? Good Luck {{!}} Cato Institute |url=https://www.cato.org/regulation/spring-2024/good-fences-good-luck |access-date=2025-05-23 |website=perma.cc |language=en-us |archive-date=March 17, 2024 |archive-url=https://web.archive.org/web/20240317131427/https://www.cato.org/regulation/spring-2024/good-fences-good-luck |url-status=bot: unknown }}</ref> 

While open fields are not protected by the Fourth Amendment, the [[curtilage]], or outdoor area immediately surrounding the home, is protected. Courts have treated this area as an extension of the house and as such subject to all the privacy protections afforded a person's home (unlike a person's open fields) under the Fourth Amendment. The curtilage is "intimately linked to the home, both physically and psychologically", and is where "privacy expectations are most heightened".<ref>''[[California v. Ciraolo]]'', {{ussc|476|207|1986|pin=213}}.</ref> However, courts have held aerial surveillance of curtilage not to be included in the protections from unwarranted search so long as the airspace above the curtilage is generally accessible by the public. An area is curtilage if it "harbors the intimate activity associated with the sanctity of a man's home and the privacies of life".<ref>''[[United States v. Dunn]]'', {{ussc|480|294|1987|pin=300}}.</ref> Courts make this determination by examining "whether the area is included within an enclosure surrounding the home, the nature of the uses to which the area is put, and the steps taken by the resident to protect the area from observation by people passing by".<ref>''Dunn'', 480 U.S. at 301.</ref> The Court has acknowledged that a doorbell or knocker is typically treated as an invitation, or license, to the public to approach the front door of the home to deliver mail, sell goods, solicit for charities, etc. This license extends to the police, who have the right to try engaging a home's occupant in a "[[knock and talk]]" for the purpose of gathering evidence without a warrant. However, they cannot bring a drug detection dog to sniff at the front door of a home without either a warrant or consent of the homeowner or resident.<ref>''Jardines'', 569 U. S. (slip op., at 6). "This implicit license typically permits the visitor to approach the home by the front path, knock promptly, wait briefly to be received, and then (absent invitation to linger longer) leave. Complying with the terms of that traditional invitation does not require fine-grained legal knowledge; it is generally managed without incident by the Nation's Girl Scouts and trick-or-treaters."</ref>

Moreover, several state courts have rejected the open fields doctrine under their own state constitutional search-and-seizure provisions.<ref>{{Cite web |title=Falkner v. State |url=https://case-law.vlex.com/vid/falkner-v-state-23233-898322517 |access-date=2025-06-04 |website=vLex |language=en}}</ref><ref>{{Cite web |title=State v. Bullock |url=https://case-law.vlex.com/vid/state-v-bullock-no-887562246 |access-date=2025-06-04 |website=vLex |language=en}}</ref><ref>{{Cite web |title=People v. Scott |url=https://case-law.vlex.com/vid/people-v-scott-887357039 |access-date=2025-06-04 |website=vLex |language=en}}</ref><ref>{{Cite web |title=State v. Dixson |url=https://law.justia.com/cases/oregon/supreme-court/1988/307-or-195.html |access-date=2025-06-04 |website=Justia Law |language=en}}</ref><ref>''Welch v. State'', 289 S.W. 510 (Tenn. 1926)</ref><ref>{{Cite web |title=State v. Kirchoff |url=https://case-law.vlex.com/vid/state-v-kirchoff-no-895039144 |access-date=2025-06-04 |website=vLex |language=en}}</ref><ref>{{Cite web |title=State v. Myrick |url=https://law.justia.com/cases/washington/supreme-court/1984/50380-0-1.html |access-date=2025-06-04 |website=Justia Law |language=en}}</ref> Moreover, several of these decisions have been reaffirmed over time.<ref>''Okhuysen v. City of Starkville'', 333 So. 3d 573, 579 (Miss. Ct. App. 2022)</ref><ref>{{Cite web |title=Terry Rainwaters, et al. v. Tennessee Wildlife Resources Agency, et al. |url=https://law.justia.com/cases/tennessee/court-of-appeals/2024/w2022-00514-coa-r3-cv.html |access-date=2025-06-04 |website=Justia Law |language=en}}</ref><ref>{{Cite web |title=State v. Dupuis |url=https://case-law.vlex.com/vid/state-v-dupuis-no-886933553 |access-date=2025-06-04 |website=vLex |language=en}}</ref><ref>{{Cite web |title=State v. Johnson |url=https://case-law.vlex.com/vid/state-v-johnson-16073-890509330 |access-date=2025-06-04 |website=vLex |language=en}}</ref>

===Exigent circumstance===

{{main|Exigent circumstance}}

Law enforcement officers may also conduct warrantless searches in several types of exigent circumstances where obtaining a warrant is dangerous or impractical. Under ''[[Terry v. Ohio]]'' (1968) police are permitted to frisk suspects for weapons.<ref name=Exigent /> The Court also allowed a search of arrested persons in ''Weeks v. United States'' (1914) to preserve evidence that might otherwise be destroyed and to ensure suspects were disarmed.<ref name=Exigent /><ref name=Weeks/> In ''Carroll v. United States'' (1925),<ref name=Carroll/> the Court ruled that law enforcement officers could search a vehicle that they suspected of carrying contraband without a warrant.<ref name=Exigent /> The Court allowed blood to be drawn without a warrant from drunk-driving suspects in ''[[Schmerber v. California]]'' (1966) on the grounds that the time to obtain a warrant would allow a suspect's [[blood alcohol content]] to reduce,<ref name=Exigent /><ref>''[[Schmerber v. California]]'', {{ussc|384|757|1966}}.</ref> although this was later modified by ''[[Missouri v. McNeely]]'' (2013).<ref>{{cite web|title=Missouri v. McNeely|url=https://www.supremecourt.gov/opinions/12pdf/11-1425_cb8e.pdf|publisher=Supreme Court|access-date=December 5, 2014|archive-date=November 14, 2014|archive-url=https://web.archive.org/web/20141114063641/http://www.supremecourt.gov/opinions/12pdf/11-1425_cb8e.pdf|url-status=dead}}</ref> ''[[Warden v. Hayden]]'' (1967) provided an exception to the warrant requirement if officers were in "hot pursuit" of a suspect.<ref name=Exigent>{{cite encyclopedia|url=http://www.highbeam.com/doc/1G2-3425000901.html|archive-url=https://web.archive.org/web/20140610085714/http://www.highbeam.com/doc/1G2-3425000901.html|url-status=dead|archive-date=June 10, 2014|title=Exigent Circumstances Search|author=Landynski, Jacob W.|year=1986|encyclopedia=Encyclopedia of the American Constitution|publisher=|access-date=July 31, 2013}}</ref><ref>''[[Warden v. Hayden]]'', {{ussc|387|294|1967}}.</ref>

A subset of exigent circumstances is the debated community caretaking exception.<ref>{{Cite web|url=http://www.abajournal.com/magazine/article/courts_in_a_muddle_over_4th_amendments_community_caretaking_exception/|title=Courts in a muddle over 4th Amendment's community caretaking exception|archiveurl= https://web.archive.org/web/20200419050933/http://www.abajournal.com/magazine/article/courts_in_a_muddle_over_4th_amendments_community_caretaking_exception/|archive-date=April 19, 2020|work=ABA Journal|access-date=2018-09-29|others=David L. Hudson|language=en}}</ref><ref>{{Cite web|url=https://www.radford.edu/content/va-chiefs/home/august-2012/community-caretaker.html|title=The Community Caretaker Function Exception to the Warrant Requirement {{!}} Virginia Police Legal Bulletin {{!}} Radford University|website=www.radford.edu|access-date=2018-09-29|archive-date=September 30, 2018|archive-url=https://web.archive.org/web/20180930033541/https://www.radford.edu/content/va-chiefs/home/august-2012/community-caretaker.html|url-status=dead}}</ref>

===Motor vehicle===

{{main|Motor vehicle exception}}

The Supreme Court has held that individuals in automobiles have a reduced expectation of privacy, because (1) vehicles generally do not serve as residences or repositories of personal effects, and (2) vehicles "can be quickly moved out of the locality or jurisdiction in which the warrant must be sought".<ref>''Carroll v. United States'', 267 U.S. 132, 153 (1925)</ref> Vehicles may not be randomly stopped and searched; there must be probable cause or reasonable suspicion of criminal activity. Items in plain view may be seized; areas that could potentially hide weapons may also be searched. With probable cause to believe evidence is present, police officers may search any area in the vehicle. However, they may not extend the search to the vehicle's passengers without probable cause to search those passengers or consent from the passengers.<ref>{{cite web|url=https://www.questia.com/read/1G1-136166930|title=The motor vehicle exception|author=Hendrie, Edward|date=August 1, 2005|work=The FBI Law Enforcement Bulletin|via= |url-access=|access-date=}}{{dead link|date=July 2021}}</ref> In ''[[Collins v. Virginia]]'' (2018),<ref>''[[Collins v. Virginia]]'', {{ussc|||2018|docket=16-1027}}</ref> the Court ruled that the motor vehicle exception did not apply to searches of vehicles parked within a residence's [[curtilage]].<ref>{{cite web|url=http://www.scotusblog.com/2018/05/opinion-analysis-justices-decline-to-extend-fourth-amendments-automobile-exception/|title=Opinion analysis: Justices decline to extend Fourth Amendment's "automobile exception"|last=Howe|first=Amy|date=May 29, 2018|publisher=[[SCOTUSblog]]|access-date=May 29, 2018}}</ref>

In ''[[Arizona v. Gant]]'' (2009),<ref>''[[Arizona v. Gant]]'', {{ussc|556|332|2009|docket=07-542}}</ref> the Court ruled that a law enforcement officer needs a warrant before searching a motor vehicle after an arrest of an occupant of that vehicle, unless 1) at the time of the search the person being arrested is unsecured and within reaching distance of the passenger compartment of the vehicle or 2) police officers have reason to believe evidence for the crime for which the person is being arrested will be found in the vehicle.<ref>{{cite web|url=http://www.scotusblog.com/2009/04/a-new-rule-for-warrantless-car-searches/|title=Limits on warrantless car searches, compensation to terrorism victims, veterans benefit disputes|last=Moore|first=Kristina|date=April 21, 2009|publisher=[[SCOTUSblog]]|access-date=April 22, 2009}}</ref>

===Searches incident to a lawful arrest===

{{main|Searches incident to a lawful arrest}}

A [[common law]] rule from Great Britain permits searches incident to an arrest without a warrant. This rule has been applied in American law, and has a lengthy common law history.<ref>[[Orin Kerr|Kerr, Orin]] (December 14, 2010) [http://volokh.com/2010/12/14/the-origins-of-the-search-incident-to-arrest-exception/ The Origins of the "Search Incident to Arrest" Exception], ''[[The Volokh Conspiracy]]''</ref> The justification for such a search is to prevent the arrested individual 1.) from destroying evidence or 2.) using a weapon against the arresting officer by disarming the suspect.<ref>{{cite web|title=''Riley v. California'' – Concerning the Constitutionality of a Warrantless Cell Phone Search Incident to Arrest|url=http://epic.org/amicus/cell-phone/riley/#background|publisher=Electronic Privacy Information Center|access-date=July 1, 2014}}</ref> The U.S. Supreme Court ruled that "both justifications for the search-incident-to-arrest exception are absent and the rule does not apply" when "there is no possibility" the suspect could gain access to a weapon or destroy evidence.<ref>''[[Arizona v. Gant]]'', {{ussc|source=f|556|332|2009|pin=339}}.</ref> In ''[[Trupiano v. United States]]'' (1948), the Supreme Court held that "a search or seizure without a warrant as an incident to a lawful arrest has always been considered to be a strictly limited right. It grows out of the inherent necessities of the situation at the time of the arrest. But there must be something more in the way of necessity than merely a lawful arrest."<ref>''[[Trupiano v. United States]]'', {{ussc|334|699|1948}}.</ref> In ''[[United States v. Rabinowitz]]'' (1950), the Court reversed ''Trupiano'', holding instead that the officers' opportunity to obtain a warrant was not germane to the reasonableness of a search incident to an arrest. ''Rabinowitz'' suggested that any area within the "immediate control" of the arrestee could be searched, but it did not define the term.<ref>''[[United States v. Rabinowitz]]'', {{ussc|339|56|1950}}.</ref> In deciding ''[[Chimel v. California]]'' (1969), the Supreme Court elucidated its previous decisions. It held that when an arrest is made, it is reasonable for the officer to search the arrestee for weapons and evidence.<ref>''[[Chimel v. California]]'', {{ussc|395|752|1969}}.</ref> However, in ''[[Riley v. California]]'' (2014), the Supreme Court ruled unanimously that police must obtain a warrant to search an arrestee's cellular phone.<ref>''[[Riley v. California]]'' {{ussc|573||2014|docket=13-132}}.</ref> The Court said that earlier Supreme Court decisions permitting searches incident to an arrest without a warrant do not apply to "modern cellphones, which are now such a pervasive and insistent part of daily life that the proverbial visitor from Mars might conclude they were an important feature of human anatomy" and noted that U.S. citizens' cellphones today typically contain "a digital record of nearly every aspect of their lives—from the mundane to the intimate".<ref>{{cite news|last1=Liptak|first1=Adam|title=Major Ruling Shields Privacy of Cellphones|url=https://www.nytimes.com/2014/06/26/us/supreme-court-cellphones-search-privacy.html?_r=0|access-date=June 25, 2014|newspaper=The New York Times|date=June 25, 2014}}</ref><ref>{{cite news|author1=Charlie Savage, Hannah Fairfield and Josh Williams|title=Between the Lines of the Cellphone Privacy Ruling|url=https://www.nytimes.com/interactive/2014/06/25/us/annotated-supreme-court-cellphone-privacy-decision.html|access-date=June 25, 2014|newspaper=The New York Times|date=June 25, 2014}}</ref>

===Border search exception===

{{main|Border search exception}}

Searches conducted at the United States border or the equivalent of the border (such as an international airport) may be conducted without a warrant or probable cause subject to the border search exception.<ref>{{Cite court|litigants=Henderson v. United States (1967)|vol=390|reporter=F.2d|opinion=805|court=9th Cir.|date=1967|url=https://scholar.google.com/scholar_case?case=16279205941356630763&hl=en&as_sdt=80000006|access-date=February 12, 2014}}</ref><ref>{{Cite court|litigants=United States v. Guadalupe-Garza|vol=421|reporter=F.2d|opinion=876|court=9th Cir.|date=1970|url=https://scholar.google.com/scholar_case?case=12470920553407736097&hl=en&as_sdt=80000006|access-date=February 12, 2014}}</ref><ref name=Upright>{{cite journal|url=https://www.questia.com/read/1G1-212208638|title=Suspicionless border seizures of electronic files: the overextension of the border search exception to the Fourth Amendment|author=Upright, Scott J.|date=October 1, 2009|journal=William and Mary Law Review|volume=51|issue=1|page=291|via= |url-access=|access-date=}}{{dead link|date=July 2021}}</ref><ref>''[[United States v. Flores-Montano]]'', {{ussc|541|149|2004}}, ''[[United States v. Montoya De Hernandez]]'', {{ussc|473|531|1985}}, and ''[[United States v. Ramsey (1977)|United States v. Ramsey]]'', {{ussc|431|606|1977}}.</ref> Most border searches may be conducted entirely at random, without any level of suspicion, pursuant to [[U.S. Customs and Border Protection]] plenary search authority. However, searches that intrude upon a traveler's personal dignity and privacy interests, such as strip and body cavity searches, must be supported by "reasonable suspicion".<ref name=Upright/><ref>''Flores-Montano'', 541 U.S. at 152–53.</ref> The [[United States courts of appeals|U.S. Courts of Appeals]] for the [[United States Court of Appeals for the Fourth Circuit|Fourth]] and [[United States Court of Appeals for the Ninth Circuit|Ninth]] circuits have ruled that information on a traveler's electronic materials, including personal files on a laptop computer, may be searched at random, without suspicion.<ref name=Upright/><ref>{{Cite court|litigants=United States v. Ickes|vol=393|reporter=F.3d|opinion=501|court=4th Cir.|date=2005|url=https://scholar.google.com/scholar_case?hl=en&as_sdt=40000006&case=6617780725605214433&scilh=0|access-date=February 12, 2014}}</ref><ref>{{Cite court|litigants=[[United States v. Arnold]]|vol=523|reporter=F.3d|opinion=941|court=9th Cir.|date=2008|url=https://scholar.google.com/scholar_case?hl=en&as_sdt=40000006&case=12655750918489961564&scilh=0|access-date=February 12, 2014}}</ref>

===Foreign intelligence surveillance===

The Supreme Court decision in ''[[United States v. U.S. District Court]]'' (1972)<ref>''[[United States v. U.S. District Court]]'', {{ussc|407|297|1972}}.</ref> left open the possibility for a foreign intelligence surveillance exception to the warrant clause.<ref name="Lawfare20130523">{{cite web|last=Vladeck|first=Steve|title=More on Clapper and the Foreign Intelligence Surveillance Exception|url=https://www.lawfaremedia.org/2012/05/more-on-clapper/|publisher=Lawfare Blog – Hard National Security Choices|access-date=July 17, 2013|date=May 23, 2013|url-status=live|archive-url=https://web.archive.org/web/20190716214424/https://www.lawfareblog.com/more-clapper-and-foreign-intelligence-surveillance-exception |archive-date=July 16, 2019}}</ref> Three United States Courts of Appeals have recognized a foreign intelligence surveillance exception to the warrant clause, but tied it to certain requirements.<ref name="Lawfare20130523"/> The exception to the Fourth Amendment was formally recognized by the [[United States Foreign Intelligence Surveillance Court of Review]] in its 2008 ''[[w:United States Foreign Intelligence Surveillance Court of Review#In re Directives|In re Directives]]''<ref name="Seyla20080822">{{cite web|author=Selya, Bruce M.|title=United States Foreign Intelligence Surveillance Court of Review Case No. 08-01 In Re Directives [redacted text] Pursuant to Section 105B of the Foreign Intelligence Surveillance Act|url=https://fas.org/irp/agency/doj/fisa/fiscr082208.pdf|publisher= [[United States Foreign Intelligence Surveillance Court of Review|U.S. Foreign Intelligence Surveillance Court of Review]] (via the [[Federation of American Scientists]])|access-date=July 15, 2013|date=August 22, 2008|archive-url=https://web.archive.org/web/20190803025150/https://fas.org/irp/agency/doj/fisa/fiscr082208.pdf|archive-date=August 3, 2019|author-link=Bruce M. Selya}}</ref> decision.<ref name="Lawfare20130522">{{cite news|last=Vladeck|first=Steve|title=Why Clapper Matters: The Future of Programmatic Surveillance|url=https://www.lawfaremedia.org/article/why-clapper-matters-future-programmatic-surveillance|access-date=July 17, 2013|newspaper=Lawfare Blog – Hard National Security Choices|date=May 22, 2013}}</ref> The lower court held that "a foreign intelligence exception to the Fourth Amendment's warrant requirement exists when surveillance is conducted to obtain foreign intelligence for national security purposes and is directed against foreign powers or agents of foreign powers reasonably believed to be located outside the United States".<ref name="Lawfare20130522" />

Despite the foregoing citation the Fourth Amendment prohibitions against unreasonable searches and seizures nonetheless apply to the contents of all communications, whatever the means, because, "a person's private communications are akin to personal papers".<ref name="FiscPrivacyRuling2011">{{cite web|url=https://www.eff.org/sites/default/files/filenode/fisc_opinion_-_unconstitutional_surveillance_0.pdf|pages=73–74|date=October 3, 2011|author=John D Bates|title=[redacted]|work=United States Foreign Intelligence Surveillance Court|archive-url=https://web.archive.org/web/20190711060421/https://www.eff.org/sites/default/files/filenode/fisc_opinion_-_unconstitutional_surveillance_0.pdf|archive-date=July 11, 2019|publisher=Electronic Frontier Foundation}}</ref> Fourth Amendment reasonableness is the point at which the United States government's interest advanced by a particular search or seizure outweighs the loss of individual privacy or freedom of movement that attends the government's action.<ref name="20060130CSRDoyle76006">{{cite web|author=Senior Specialist Charles Doyle|title=CSR Memorandum to the United Senate Select Committee on Intelligence entitled "Probable Cause, Reasonable Suspicion, and Reasonableness Standards in the Context of the Fourth Amendment and the Foreign Intelligence Act"|url=https://fas.org/sgp/crs/intel/m013006.pdf|publisher=Congressional Research Service via the [[Federation of American Scientists]]|access-date=September 27, 2019|date=January 30, 2006|pages=1 and 6–8}}</ref> The United Supreme Court said in ''[[Board of Education v. Earls]]'' (2002)<ref>''[[Board of Education v. Earls]]'', {{ussc|536|822|2002}}</ref> when 'special needs', beyond the normal need for law enforcement, make the warrant and probable-cause requirement impracticable the reasonableness of a search is determined by balancing the nature of the intrusion on the individual's privacy against the promotion of legitimate governmental interests.<ref name="20060130CSRDoyle76006" /> Additionally in ''[[Illinois v. Lidster]]'' (2004)<ref>''[[Illinois v. Lidster]]'', {{ussc|540|419|2004}}</ref> the Court explained in judging reasonableness it looks to "the gravity of the public concerns served by the seizure, the degree to which the seizure advances the public interest, and the severity of the interference with individual liberty".<ref name="20060130CSRDoyle76006" /> To protect the [[telecommunications carrier]]s cooperating with the U.S. government from legal action, the Congress passed [[Foreign Intelligence Surveillance Act of 1978 Amendments Act of 2008|a bill]] updating the [[Foreign Intelligence Surveillance Act]] of 1978 to permit this type of surveillance.<ref>{{cite news|last1=Ferraro|first1=Thomas|title=Bush wins passage of US spy bill to protect telecoms|url=https://www.reuters.com/article/us-usa-surveillance/bush-wins-passage-of-spy-bill-to-protect-telecoms-idUSWAT00975320080710|access-date=September 27, 2019|work=Reuters|publisher=Reuters|date=July 9, 2008}}</ref>

===Schools and prisons===

In ''[[New Jersey v. T. L. O.]]'' (1985), the Supreme Court ruled that searches in [[Public education|public schools]] do not require warrants, as long as the searching officers have reasonable grounds for believing the search will result in finding evidence of illegal activity.<ref name=TLO /> Similarly, in ''[[Samson v. California]]'' (2006), the Court ruled that government offices may be searched for evidence of work-related misconduct by government employees on similar grounds.<ref>''[[Samson v. California]]'', {{ussc|547|843|2006}}.</ref> Searches of prison cells are subject to no restraints relating to reasonableness or probable cause.<ref>{{cite journal|url=http://scholarlycommons.law.northwestern.edu/cgi/viewcontent.cgi?article=6436&context=jclc|title=Fourth Amendment—Prison Cells: Is there a Right to Privacy|author=Goring, Darlene C.|journal=Journal of Criminal Law and Criminology|volume=75|issue=3|pages=609–629|access-date=September 19, 2013|year=1984|doi=10.2307/1143635|jstor=1143635|url-access=subscription}}</ref> However, in ''[[Safford Unified School District v. Redding]]'' (2009),<ref>''[[Safford Unified School District v. Redding]]'', {{ussc|557||2009|docket=08-479}}.</ref> the Court ruled that school officials violated the Fourth Amendment when they [[strip searched]] a student based only on another student's claiming to have received drugs from her.<ref>{{cite web|url=http://www.scotusblog.com/2009/06/analysis-some-expansion-of-student-privacy/|title=Analysis: Some expansion of student privacy|last=Denniston|first=Lyle|date=June 25, 2009|publisher=[[SCOTUSblog]]|access-date=June 25, 2009}}</ref>

==Exclusionary rule==<!-- This section is linked from [[Sheriff]] -->

{{main|Exclusionary rule}}

One way courts enforce the Fourth Amendment is through the use of the exclusionary rule. The rule provides that evidence obtained through a violation of the Fourth Amendment is generally not [[Admissible evidence|admissible]] by the prosecution during the defendant's criminal trial.<ref name=Exclusionary>{{cite encyclopedia|url=http://www.highbeam.com/doc/1G2-3425000884.html|archive-url=https://web.archive.org/web/20131111045052/http://www.highbeam.com/doc/1G2-3425000884.html|url-status=dead|archive-date=November 11, 2013|title=Exclusionary Rule|author=Levy, Leonard W.|year=1986|encyclopedia=Encyclopedia of the American Constitution|publisher=|access-date=July 31, 2013}}</ref> The Court stated in ''[[Elkins v. United States]]'' (1960)<ref>''[[Elkins v. United States]]'', {{ussc|364|206|1960}}.</ref> that the rule's function "is to deter—to compel respect for the constitutional guaranty in the only effectively available way—by removing the incentive to disregard it".<ref name=Exclusionary/>

The Court adopted the exclusionary rule in ''[[Weeks v. United States]]'' (1914),<ref name=Weeks>''[[Weeks v. United States]]'', {{ussc|232|383|1914}}.</ref> prior to which all evidence, no matter how seized, could be admitted in court.<ref>{{cite encyclopedia|url=http://www.highbeam.com/doc/1G2-3425002689.html |archive-url=https://web.archive.org/web/20140610085525/http://www.highbeam.com/doc/1G2-3425002689.html |url-status=dead |archive-date=June 10, 2014 |title=Weeks v. United States 232 U.S. 383 (1914)|author=Landynski, Jacob W.|year=1986|encyclopedia=Encyclopedia of the American Constitution|publisher=|access-date=July 31, 2013}}</ref> In ''[[Silverthorne Lumber Co. v. United States]]'' (1920)<ref>''[[Silverthorne Lumber Co. v. United States]]'', {{ussc|251|385|1920}}.</ref> and ''[[Nardone v. United States]]'' (1939),<ref>''[[Nardone v. United States]]'', {{ussc|308|338|1939}}.</ref> the Court ruled that leads or other evidence resulting from illegally obtained evidence are also inadmissible in trials. Justice [[Felix Frankfurter]] described this secondary evidence in the ''Nardone'' decision as the "[[fruit of the poisonous tree]]".<ref>{{cite encyclopedia|url=http://www.highbeam.com/doc/1G2-3425002308.html |archive-url=https://web.archive.org/web/20140610085519/http://www.highbeam.com/doc/1G2-3425002308.html |url-status=dead |archive-date=June 10, 2014 |title=Silverthorne Lumber Co. v. United States 251 U.S. 385 (1920)|author=Landynski, Jacob W.|year=1986|encyclopedia=Encyclopedia of the American Constitution|publisher=|access-date=July 31, 2013}}</ref> The Supreme Court rejected incorporating the exclusionary rule by way of the Fourteenth Amendment in ''[[Wolf v. Colorado]]'' (1949),<ref>''[[Wolf v. Colorado]]'', {{ussc|338|25|1949}}.</ref> but ''Wolf'' was explicitly overruled in ''Mapp v. Ohio'' (1961),<ref name=Mapp/> making the Fourth Amendment (including the exclusionary rule) applicable in state proceedings.<ref>{{cite web|url=http://www.highbeam.com/doc/1G2-3457000098.html|archive-url=https://web.archive.org/web/20140610085521/http://www.highbeam.com/doc/1G2-3457000098.html|url-status=dead|archive-date=June 10, 2014|title=Mapp v. Ohio|year=2001|work=Supreme Court Drama: Cases That Changed America|publisher=|access-date=July 31, 2013}}</ref>

The exclusionary rule and its effectiveness have often been controversial, particularly since its 1961 application to state proceedings. Critics charge that the rule hampers police investigation and can result in freeing guilty parties convicted on reliable evidence; other critics say the rule has not been successful in deterring illegal police searches. Proponents argue that the number of criminal convictions overturned under the rule has been minimal and that no other effective mechanism exists to enforce the Fourth Amendment.<ref name=Exclusionary/> In 1982, [[California]] passed a "[[California Proposition 8 (1982)|Victim's Bill of Rights]]" containing a provision to repeal the exclusionary rule; though the bill could not affect federally mandated rights under the Fourth Amendment, it blocked the state courts from expanding these protections further.<ref>{{cite web|url=https://www.nytimes.com/1982/06/21/opinion/california-s-backfire-on-crime.html|title=California's Backfire on Crime|date=June 21, 1982|work=The New York Times|access-date=July 31, 2013}}</ref>{{sfnp|Crisera|1990|p=1587}}

===Limitations===

Since 1974, the Supreme Court has repeatedly limited the exclusionary rule.<ref name=Exclusionary/> In ''[[United States v. Calandra]]'' (1974),<ref>''[[United States v. Calandra]]'', {{ussc|414|338|1974}}.</ref> the Court ruled that [[grand juries]] may use illegally obtained evidence when questioning witnesses, because "the damage to that institution from the unprecedented extension of the exclusionary rule outweighs the benefit of any possible incremental deterrent effect".<ref>''Calandra'', 414 U.S. at 354.</ref> Explaining the purpose of the rule, the Court said the rule "is a judicially created remedy designed to safeguard Fourth Amendment rights generally through its deterrent effect, rather than a personal constitutional right of the party aggrieved".<ref>''Calandra'', 414 U.S. at 349.</ref>

Three cases in 1984 further restricted the exclusionary rule:
* In ''[[United States v. Leon]]'' (1984),<ref>''[[United States v. Leon]]'', {{ussc|468|897|1984}}.</ref> the Court established the "good faith" exception to the rule, ruling that evidence seized by officers reasonably relying on a warrant was still admissible, even though the warrant was later found to be defective, unless an officer dishonestly or recklessly prepared an affidavit to seek a warrant, the issuing magistrate abandoned his neutrality, or the warrant lacked sufficient particularity.<ref>''Leon'', 468 U.S. at 926.</ref>
* The Court determined in ''[[Nix v. Williams]]'' (1984)<ref>''[[Nix v. Williams]]'', {{ussc|467|431|1984}}.</ref> that "fruit of the poisonous tree" evidence could still be introduced if a prosecutor could demonstrate that it would have been an "inevitable discovery" of legitimate investigation.<ref>{{cite encyclopedia|url=http://www.highbeam.com/doc/1G2-3425001776.html|archive-url=https://web.archive.org/web/20140610085517/http://www.highbeam.com/doc/1G2-3425001776.html|url-status=dead|archive-date=June 10, 2014|title=Nix v. Williams 467 U.S. 431 (1984)|author=Levy, Leonard W.|year=1986|encyclopedia=Encyclopedia of the American Constitution|publisher=|access-date=July 31, 2013}}</ref>
* In ''[[Segura v. United States]]'' (1984),<ref>''[[Segura v. United States]]'', {{ussc|468|796|1984}}.</ref> the Court ruled that evidence illegally found without a search warrant is admissible if the evidence is later found and legally seized based on information independent of the illegal search.<ref>{{cite web|url=https://www.questia.com/read/1G1-54061501|title=The Inevitable Discovery Exception to the Exclusionary Rule|author=Hendrie, Edward M.|date=September 1, 1997|work=The FBI Law Enforcement Bulletin|publisher=|url-access=|access-date=}}{{dead link|date=July 2021}}</ref>

In ''[[Arizona v. Evans]]'' (1995)<ref>''[[Arizona v. Evans]]'', {{ussc|514|1|1995}}.</ref> and ''[[Herring v. United States]]'' (2009),<ref>''[[Herring v. United States]]'', {{ussc|555|135|2009}}.</ref> the Court ruled that the exclusionary rule does not apply to evidence found due to negligence regarding a government database, as long as the arresting police officer relied on that database in "good faith" and the negligence was not pervasive.<ref>{{cite web|url=http://law.richmond.edu/jolt/v2i1/stinger.html|title=''Arizona v. Evans'': Adapting the Exclusionary Rule to Advancing Computer Technology|last=Stinger|first=C. Maureen|date=February 13, 1996|publisher=The Richmond Journal of Law and Technology|access-date=January 16, 2009}}</ref><ref>{{cite web|url=http://www.law.com/jsp/scm/PubArticleSCM.jsp?id=1202427461021|access-date=January 14, 2009|title=Court says evidence is valid despite police error}}</ref> In ''[[Davis v. United States (2011)|Davis v. United States]]'' (2011),<ref>''[[Davis v. United States (2011)|Davis v. United States]]'', 131 S.Ct. 2419, {{ussc|564||2011|docket=09-11328}}.</ref> the Court ruled that the exclusionary rule does not apply to a Fourth Amendment violation resulting from a reasonable reliance on binding appellate precedent.<ref>{{cite web|url=http://www.scotusblog.com/?p=122938|title=Opinion analysis: The fading "exclusionary rule"|last=Denniston|first=Lyle|date=June 25, 2011|publisher=[[SCOTUSblog]]|access-date=November 25, 2011|archive-date=May 22, 2013|archive-url=https://web.archive.org/web/20130522120026/http://www.scotusblog.com/?p=122938|url-status=dead}}</ref> In ''[[Utah v. Strieff]]'' (2016),<ref>''[[Utah v. Strieff]]'', {{ussc|579||2016|docket=14-1373}}</ref> the Court ruled that evidence obtained from an unlawful police stop would not be excluded from court when the link between the stop and the evidence's discovery was "attenuated" by the discovery of an outstanding warrant during the stop.<ref>{{cite news |last1=Waimberg |first1=Joshua |title=The Supreme Court's Utah v. Strieff decision and the Fourth Amendment |url=http://blog.constitutioncenter.org/2016/06/the-supreme-courts-utah-v-strieff-decision-and-the-fourth-amendment/ |access-date=June 25, 2016 |work=[[National Constitution Center]] |publisher=[[National Constitution Center]] |archive-url=https://web.archive.org/web/20160623144514/http://blog.constitutioncenter.org/2016/06/the-supreme-courts-utah-v-strieff-decision-and-the-fourth-amendment/|archive-date=June 23, 2016}}</ref>

The Supreme Court has also held the exclusionary rule to not apply in the following circumstances:
* evidence illegally seized by a "private actor" (i.e., not a governmental employee)<ref>''[[Burdeau v. McDowell]]'', {{ussc|256|465|1921}}.</ref>
* tax hearings<ref>''[[United States v. Janis]]'', {{ussc|428|433|1976}}.</ref>
* evidence collected by U.S. Customs agents<ref>''[[United States v. Andreas]]'', {{ussc|463|765|1983}}.</ref>
* deportation hearings<ref>''[[INS v. Lopez-Mendoza]]'', {{ussc|468|1032|1984}}.</ref>
* evidence seized by probation or parole officers<ref>''[[Griffin v. Wisconsin]]'', {{ussc|483|868|1987}}; ''[[United States v. Knights (2001)|United States v. Knights]]'', {{ussc|534|112|2001}}.</ref>
* probation or parole revocation hearings<ref>''[[Pennsylvania Bd. of Probation and Parole v. Scott]]'', {{ussc|524|357|1998}}.</ref>

==Metadata==

{{See also|Global surveillance disclosures (2013–present)|Upstream collection|Mass surveillance|Targeted surveillance}}

On December 16, 2013, in ''[[Klayman v. Obama]]'', a [[United States district court]] ruled that the mass collection of [[metadata]] of Americans' telephone records by the National Security Agency probably violates the Fourth Amendment.<ref>{{cite news|last=Leon|first=Richard|title=Federal judge rules NSA program is likely unconstitutional|url=https://apps.washingtonpost.com/g/page/world/federal-judge-rules-nsa-program-is-likely-unconstitutional/668/|access-date=December 17, 2013|newspaper=The Washington Post|date=December 16, 2013|archive-date=August 30, 2017|archive-url=https://web.archive.org/web/20170830105413/https://apps.washingtonpost.com/g/page/world/federal-judge-rules-nsa-program-is-likely-unconstitutional/668/|url-status=dead}}</ref><ref>{{cite news|last=Savage|first=Charlie|title=Judge Questions Legality of N.S.A. Phone Records|url=https://www.nytimes.com/2013/12/17/us/politics/federal-judge-rules-against-nsa-phone-data-program.html|access-date=December 18, 2013|newspaper=The New York Times|date=December 16, 2013}}</ref><ref>{{cite news|title=Judge: NSA domestic phone data-mining unconstitutional|url=https://edition.cnn.com/2013/12/16/justice/nsa-surveillance-court-ruling/|publisher=CNN|access-date=December 18, 2013|author1=Bill Mears|author2=Evan Perez|date=December 17, 2013}}</ref><ref>{{cite news|last=Kravets|first=David|title=Court Says NSA Bulk Telephone Spying Is Unconstitutional|url=https://www.wired.com/threatlevel/2013/12/bulk-telephone-metada-ruling/|access-date=December 18, 2013|date=December 16, 2013|magazine=Wired}}</ref><ref>{{cite news|title=Federal judge rules against NSA spying|url=https://www.usatoday.com/story/news/nation/2013/12/16/judge-nsa-surveillance-fourth-amendment/4041995/|access-date=December 18, 2013|newspaper=USA Today|date=December 16, 2013|author1=Kevin Johnson|author2=Richard Wolf}}</ref><ref>{{cite news|last=Gerstein|first=Josh|title=Judge: NSA phone program likely unconstitutional|url=https://www.politico.com/story/2013/12/national-security-agency-phones-judge-101203.html|access-date=December 18, 2013|newspaper=Politico|date=December 16, 2013}}</ref><ref name="WP20131216" /> The court granted a preliminary injunction, blocking the collection of phone data for two private plaintiffs<ref name="Guaraian20131216">{{cite news|title=NSA phone surveillance program likely unconstitutional, federal judge rules|url=https://www.theguardian.com/world/2013/dec/16/nsa-phone-surveillance-likely-unconstitutional-judge|access-date=December 18, 2013|newspaper=The Guardian|author1=Spencer Ackerman|author2=Dan Roberts|date=December 16, 2013}}</ref> and ordered the government to destroy any of their records that have been gathered. The court stayed the ruling pending a government appeal, recognizing the "significant national security interests at stake in this case and the novelty of the constitutional issues".<ref name="WP20131216">{{cite news|title=Judge: NSA's collecting of phone records is probably unconstitutional|url=https://www.washingtonpost.com/national/judge-nsas-collecting-of-phone-records-is-likely-unconstitutional/2013/12/16/6e098eda-6688-11e3-a0b9-249bbb34602c_story.html|access-date=December 17, 2013|newspaper=The Washington Post|date=December 16, 2013|author1=Ellen Nakashima|author2=Ann E. Marimow}}</ref>

However, in ''[[ACLU v. Clapper]]'', a United States district court ruled that the U.S. government's global telephone data-gathering system is needed to thwart potential terrorist attacks, and that it can work only if everyone's calls are included.<ref>{{cite web|last=Pauley III|first=William H.|title=United States District Court Southern District of New York: American Civil Liberties Union v. James R. Clapper (13 Civ. 3994) (WHP))|url=https://www.aclu.org/files/assets/order_granting_governments_motion_to_dismiss_and_denying_aclu_motion_for_preliminary_injunction.pdf|publisher=American Civil Liberties Union|access-date=December 28, 2013|date=December 27, 2013}}</ref> The court also ruled that Congress legally set up the program and it does not violate anyone's constitutional rights. The court concluded that the telephone data being swept up by NSA did not belong to telephone users, but to the telephone companies. Also, the court held that when NSA obtains such data from the telephone companies, and then probes into it to find links between callers and potential terrorists, this further use of the data was not even a search under the Fourth Amendment, concluding that the controlling precedent is ''[[Smith v. Maryland]]'', saying: "Smith's bedrock holding is that an individual has no legitimate expectation of privacy in information provided to third parties."<ref>{{cite news|title=Judge Upholds N.S.A.'s Bulk Collection of Data on Calls|url=https://www.nytimes.com/2013/12/28/us/nsa-phone-surveillance-is-lawful-federal-judge-rules.html?pagewanted=all|access-date=December 28, 2013|newspaper=The New York Times|date=December 27, 2013|author1=Adam Liptak|author2=Michael S. Schmidt}}</ref><ref>{{cite web|last=Denniston|first=Lyle|title=Judge upholds NSA's phone data sweeps (UPDATED)|url=http://www.scotusblog.com/2013/12/judge-upholds-nsas-phone-data-sweeps/|publisher=Scotusblog|access-date=December 28, 2013|date=December 27, 2013}}</ref><ref>{{cite news|last=Peterson|first=Andrea|title=The most Kafkaesque paragraph from today's NSA ruling|url=https://www.washingtonpost.com/blogs/the-switch/wp/2013/12/27/the-most-kafkaesque-paragraph-from-todays-nsa-ruling/?wprss=rss_business|access-date=December 28, 2013|newspaper=The Washington Post|date=December 27, 2013}}</ref><ref>{{cite news|last=Horwitz|first=Sari|title=NSA collection of phone data is lawful, federal judge rules|url=https://www.washingtonpost.com/world/national-security/nsa-collection-of-phone-data-is-lawful-federal-judge-rules/2013/12/27/4b99d96a-6f19-11e3-a523-fe73f0ff6b8d_story.html|access-date=December 28, 2013|newspaper=The Washington Post|date=December 27, 2013}}</ref> The [[American Civil Liberties Union]] declared on January 2, 2014, that it will appeal the ruling that NSA bulk phone record collection is legal. "The government has a legitimate interest in tracking the associations of suspected terrorists, but tracking those associations does not require the government to subject every citizen to permanent surveillance", deputy ACLU legal director Jameel Jaffer said in a statement.<ref>{{cite news|last=Ackermann|first=Spencer|title=ACLU will appeal ruling that NSA bulk phone record collection is legal|url=https://www.theguardian.com/world/2014/jan/02/aclu-appeal-nsa-bulk-phone-record-collection|access-date=January 4, 2014|newspaper=The Guardian|date=January 2, 2014}}</ref>

==See also==

{{Div col}}
* [[Article 8 of the European Convention on Human Rights]]
* [[Fourth Amendment Protection Act]]
* [[NSA warrantless surveillance (2001–07)#Fourth Amendment issues]]
* [[Parallel construction]]
* [[Privacy laws of the United States]]
* [[Special needs exception]]
* [[Section Eight of the Canadian Charter of Rights and Freedoms]]
* ''[[subpoena ad testificandum]]''
* ''[[subpoena duces tecum]]''
* [[Warrantless searches in the United States]]
{{Div col end}}

==Notes==

{{notelist}}

'''Citations'''
{{reflist|30em}}

==References==

{{refbegin}}
* {{cite book|last1=Adams|first1=Charles Francis|first2=John|last2=Adams|year=1856|title=The Works of John Adams, Second President of the United States: With a Life of the Author|volume=1 |publisher=Little, Brown}}
* {{Cite book|last=Beeman|first=Richard|year=2009|title=Plain, Honest Men: The Making of the American Constitution|publisher=Random House}}
* {{Cite journal|last=Crisera|first=Maria Lisa|title=Reevaluation of the California Corpus Delicti Rule: A Response to the Invitation of Proposition 8|journal=California Law Review|volume=78|issue=6|pages=1571–1597|year=1990|doi=10.2307/3480804|jstor=3480804|url=https://scholarship.law.berkeley.edu/californialawreview/vol78/iss6/4|url-access=subscription}}{{Dead link|date=December 2023 |bot=InternetArchiveBot |fix-attempted=yes }}
* {{cite journal|title=Recovering the Original Fourth Amendment|last=Davies|first=Thomas Y.|journal=[[Michigan Law Review]]|year=1999|volume=98|pages=547–750|doi=10.2307/1290314|issue=3|jstor=1290314|url=https://repository.law.umich.edu/mlr/vol98/iss3/2|url-access=subscription}}
* {{cite book|editor1-last=Kilman|editor1-first=Johnny|editor2-first=George|editor2-last=Costello|year=2006|title=The Constitution of the United States of America: Analysis and Interpretation|publisher=GPO}}
* {{Cite book|last=Labunski|first=Richard E.|year=2006|title=James Madison and the struggle for the Bill of Rights|publisher=Oxford University Press}}
* {{Cite book|last=Lasson|first=Nelson B.|year=1937|title=The History and Development of the Fourth Amendment to the United States Constitution|publisher=Johns Hopkins University Press}}
* {{Cite book|last=Levy|first=Leonard Williams|year=1995|title=Seasoned Judgments: The American Constitution, Rights, and History|publisher=Transaction Publishers}}
* {{Cite book|last=Maier|first=Pauline|year=2010|title=Ratification: The People Debate the Constitution, 1787–1788|publisher=Simon and Schuster}}
* {{Cite book|last=Wood|first=Gordon S.|year=2009|title=Empire of Liberty: A History of the Early Republic, 1789–1815|publisher=Oxford University Press}}
* {{Cite book|editor1-first=Kinvin|editor1-last=Wroth|editor2-first=Hiller B.|editor2-last=Zobel|year=1965|title=Legal Papers of John Adams|volume=2|publisher=Belknap Press}}
* {{cite book |title=Fourth Amendment Lesson Plan |url=https://www.eff.org/files/filenode/1211_fourth_amendment_-_lp.pdf |date=February 10, 2010 |publisher=U.S. Department of Homeland Security, Federal Law Enforcement Training Center }}
{{refend}}

==External links==
{{Wikiquote}}
* [https://www.law.cornell.edu/anncon/html/amdt4toc_user.html CRS Annotated Constitution: Fourth Amendment], [[Cornell University]]

{{US4thAmendment}}
{{US Constitution}}
{{Authority control}}

[[Category:United States Fourth Amendment case law| ]]
[[Category:1791 in American law]]
[[Category:1791 in American politics]]
[[Category:United States Bill of Rights|04]]
[[Category:Government documents of the United States]]
[[Category:Police legislation]]
[[Category:Privacy law in the United States|+]]
[[Category:Searches and seizures]]
[[Category:United States criminal constitutional law]]
[[Category:Amendments to the United States Constitution|04]]