View source for Australian Senate


{{Short description|Upper house of the Parliament of Australia}}
{{Use dmy dates|date=February 2018}}
{{Use Australian English|date=July 2016}}
{{Infobox legislature
|background_color  = firebrick
|name              = Senate
|legislature       = [[48th Parliament of Australia]]
|house_type        = Upper house
|coa_pic           = Coat of Arms of Australia.svg
|body              = Parliament of Australia
|leader1_type      = [[President of the Senate (Australia)|President]]
|leader1           = [[Sue Lines]]
|party1            = [[Australian Labor Party|Labor]]
|election1         = 26 July 2022
|leader2_type      = [[Leader of the Government in the Senate (Australia)|Leader of the Government]]
|leader2           = [[Penny Wong]]
|party2            = [[Australian Labor Party|Labor]]
|election2         = 1 June 2022
|leader3_type      = [[Manager of Government Business in the Senate|Manager of Government Business]]
|leader3           = [[Katy Gallagher]]
|party3            = [[Australian Labor Party|Labor]]
|election3         = 1 June 2022
|leader4_type      = [[Leader of the Opposition in the Senate (Australia)|Leader of the Opposition]]
|leader4           = [[Michaelia Cash]]
|party4            = [[Liberal Party of Australia|Liberal]]
|election4         = 25 January 2025
|leader5_type      = [[Manager of Opposition Business in the Senate|Manager of Opposition Business]]
|leader5           = [[Jonathon Duniam]] 
|party5            = [[Liberal Party of Australia|Liberal]]
|election5         = 25 January 2025
|members           = 76
|structure1        = File:2025 Australian Senate - Composition of Members.svg|structure1_res    = 255px
|political_groups1 = {{Composition of Australian Senate}}
|term_length       = 6 years (state senators)<br>{{nowrap|3 years (territory senators)}}
|voting_system1    = [[Proportional representation]] ([[single transferable vote]])
|last_election1    = [[2025 Australian federal election|3 May 2025]]<br />([[2025 Australian Senate election|Half Senate election]])
|next_election1    = [[Next Australian federal election|On or before 20 May 2028]]
|session_room      = Australian Senate - Parliament of Australia.jpg
|meeting_place     = Senate Chamber<br />[[Parliament House, Canberra|Parliament House]]<br />[[Canberra]], Australian Capital Territory,<br />Australia
|website           = {{URL|aph.gov.au/About_Parliament/Senate|Senate}}
}}
{{Politics of Australia sidebar}}

The '''Senate''' is the [[upper house]] of the [[Bicameralism|bicameral]] [[Parliament of Australia]], the [[lower house]] being the [[Australian House of Representatives|House of Representatives]].

The powers, role and composition of the Senate are set out in Chapter I of the [[Constitution of Australia|federal constitution]] as well as federal legislation and [[Constitutional convention (political custom)|constitutional convention]]. There are a total of 76 senators: 12 are elected from each of the six [[states and territories of Australia|Australian states]], regardless of population, and 2 each representing the [[Australian Capital Territory]] (including the [[Jervis Bay Territory]] and [[Norfolk Island]]) and the [[Northern Territory]] (including the [[Australian Indian Ocean Territories]]).<ref>{{cite web |url=https://www.aph.gov.au/senators_and_members |work=Parliament of Australia |title=Senators and Members |access-date=8 October 2025}}</ref> Senators are popularly elected under the [[single transferable vote]] system of [[proportional representation]] in state-wide and territory-wide districts.

[[Section 24 of the Constitution of Australia|Section 24]] of the Constitution provides that the House of Representatives shall have, as near as practicable, twice as many members as the Senate. The constitution grants the Senate nearly equivalent powers to the House, with the exception that the Senate may not originate or amend [[money bill]]s, but only reject or defer them. According to convention, the Senate plays no role in the formation of the [[Australian Government|executive government]] and the [[prime minister of Australia|prime minister]] is drawn from the majority party or coalition in the House. However, the government appoints a [[Leader of the Government in the Senate (Australia)|Senate leader]] and senators hold senior roles in the government as [[Minister of State (Australia)|ministers of state]] and members of [[Cabinet of Australia|cabinet]]. Senators from [[Opposition (Australia)|the opposition]] likewise serve in the [[Shadow ministry of Australia|shadow ministry]].

The Senate elects one of its members to serve as [[President of the Senate (Australia)|president]], who exercises only an ordinary vote and has no [[casting vote]]. Since the late 20th century, it has been rare for governments to hold a majority in the Senate and the [[Balance of power (parliament)|balance of power]] has typically rested with [[Political parties in Australia|minor parties]] and [[Independent politician|independents]]. In practice, this means government bills cannot be assured of passage and regulations may be disallowed. The power to bring down the government and force elections by blocking [[Confidence and supply|supply]] also exists, as happened for the first and only time during the [[1975 Australian constitutional crisis|1975 constitutional crisis]]. Since major reforms in 1970, the Senate's role as a house of review has increased with the expansion of its [[Australian Senate committees|committee system]].

Senators from states ordinarily serve six-year terms, with half of the Senate up for re-election at each [[Elections in Australia|federal election]] along with the entirety of the House of Representatives. However, there is no constitutional requirement that Senate and House elections occur at the same time; the last Senate-only and House-only elections occurred [[1970 Australian Senate election|in 1970]] and [[1972 Australian federal election|1972 respectively]]. The terms of senators from territories expire at the dissolution of the House of Representatives, typically at three-year intervals. [[Section 57 of the Constitution of Australia|Section 57]] of the constitution provides for a [[double dissolution]] as a mechanism to break deadlocks between the House and Senate, whereby the entire Senate is dissolved and all seats made vacant.

[[Casual vacancies in the Australian Parliament|Casual vacancies]] are filled by the relevant state or territory parliament, or by the corresponding state or territory government on an interim basis if the parliament is not in session. [[1977 Australian referendum (Senate Casual Vacancies)|A constitutional amendment]] passed in 1977 provides that casual vacancies must be filled by a member of the same political party as the previous senator.

==Origins and role==
[[File:Australian Senate 1923.jpg|thumb|The Australian Senate in 1923]]
The [[Constitution of Australia]] established the Senate as the second chamber of the national parliament of the newly [[Federation of Australia|federated Australia]]. In contrast to countries employing a pure [[Westminster system]] the Senate plays an active role in legislation and is not merely a chamber of review. Instead of being modelled solely after the [[House of Lords]], as the [[Senate of Canada]] was, the Australian Senate was in part modelled after the [[United States Senate]], by giving equal representation to each state and almost equal powers with the lower house.<ref name="Part V">{{Cite web|url=http://www.aph.gov.au/About_Parliament/Senate/Powers_practice_n_procedures/~/link.aspx?_id=AFF6CA564BC3465AA325E73053DED4AA&_z=z#chapter-01_part-05_53|title=Part V – Powers of the Parliament|language=en-AU|access-date=13 May 2017|archive-date=5 May 2017|archive-url=https://web.archive.org/web/20170505192600/http://www.aph.gov.au/About_Parliament/Senate/Powers_practice_n_procedures/~/link.aspx?_id=AFF6CA564BC3465AA325E73053DED4AA&_z=z#chapter-01_part-05_53|url-status=live}}</ref><ref>{{cite book| last = Viglianti-Northway| first = Karena| title = The Intentions of the Framers of the Australian Constitution Regarding Responsible Government and Accountability of the Commonerslth Executive to the Australian Senate| publisher = University of Technology Sydney| year = 2020| url = https://opus.lib.uts.edu.au/bitstream/10453/140943/2/02whole.pdf| access-date = 5 September 2020| archive-date = 3 March 2021| archive-url = https://web.archive.org/web/20210303184433/https://opus.lib.uts.edu.au/bitstream/10453/140943/2/02whole.pdf| url-status = live}}</ref> This was done to give less populous states a real influence in the Parliament, while also maintaining the traditional review functions upper houses have in the Westminster system. This has led to the description of a "[[Westminster system#"Washminster system"|Washminster system]]" to describe the Australian political structure.<ref>{{Cite web |title=How have the British and US systems of government influenced the Australian government system? |url=https://peo.gov.au/understand-our-parliament/your-questions-on-notice/ |access-date=2023-12-05 |website=Parliamentary Education Office |language=en |archive-date=12 March 2023 |archive-url=https://webarchive.nla.gov.au/awa/20230312065832/https://peo.gov.au/understand-our-parliament/your-questions-on-notice/questions/what-are-reserve-powers/ |url-status=live }}</ref><ref>{{cite journal |last=Thompson |first=Elaine |date=1980 |title=The "Washminster" Mutation |url=https://www.tandfonline.com/doi/abs/10.1080/00323268008401755 |journal=Australian Journal of Political Science |volume=15 |issue=2 |pages=32–40 |doi=10.1080/00323268008401755 |url-access=subscription |via=Taylor & Francis Online |doi-access= |access-date=17 December 2023 |archive-date=18 December 2023 |archive-url=https://web.archive.org/web/20231218151705/https://www.tandfonline.com/doi/abs/10.1080/00323268008401755 |url-status=live }}</ref><ref>{{Cite journal |last=Thompson |first=Elaine |date=2001 |title=The Constitution and the Australian System of Limited Government, Responsible Government and Representative Democracy: Revisiting the Washminster Mutation |url=https://www.austlii.edu.au/cgi-bin/viewdoc/au/journals/UNSWLJ/2001/53.html |journal=University of New South Wales Law Journal |volume=24 |issue=3 |via=[[Austlii]] |access-date=17 December 2023 |archive-date=18 December 2023 |archive-url=https://web.archive.org/web/20231218151901/https://www.austlii.edu.au/cgi-bin/viewdoc/au/journals/UNSWLJ/2001/53.html |url-status=live }}</ref>

Although the [[Prime Minister of Australia|prime minister]] and [[Treasurer of Australia|treasurer]], by convention (though not legal requirement), are members of the House of Representatives (after [[John Gorton]] was appointed prime minister in 1968, he resigned from the Senate and was elected to the House), other ministers may come from either house,<ref name="senatebrief14">{{cite web |url=http://www.aph.gov.au/About_Parliament/Senate/Powers_practice_n_procedures/Senate_Briefs/Brief14 |title=No. 14 – Ministers in the Senate |date=December 2016 |website=Senate Briefs |publisher=Parliament of Australia |access-date=31 December 2016 |archive-date=31 December 2016 |archive-url=https://web.archive.org/web/20161231170531/http://www.aph.gov.au/About_Parliament/Senate/Powers_practice_n_procedures/Senate_Briefs/Brief14 |url-status=live }}</ref> and the two Houses have almost equal legislative power.<ref name="Part V"/> As with most upper chambers in [[bicameralism|bicameral parliament]]s, the Senate cannot introduce or amend [[appropriation bill]]s (bills that authorise government expenditure of public revenue) or bills that impose taxation, that role being reserved for the lower house; it can only approve, reject or defer them (as famously occurred in the lead up to [[1975 Australian constitutional crisis|the Dismissal]]). That degree of equality between the Senate and House of Representatives reflects the desire of the Constitution's authors to prevent the more populous states totally dominating the legislative process.

In practice, however, most legislation (except for [[private member's bill]]s) in the Australian Parliament is initiated by the government, which has control over the lower house. It is then passed to the Senate, which has the opportunity to amend the bill, pass or reject it. In the majority of cases, voting takes place along [[Party line (politics)|party lines]], although there are occasional [[conscience vote]]s.

The Senate maintains [[Australian senate committees|a number of committees]], which engage in a wide variety of inquiries. The results have no direct legislative power, but are valuable forums that raise many points of view that would otherwise not receive government or public notice.<ref>{{Cite web |last= |first= |title=Information on Senate Committees |url=https://www.aph.gov.au/Parliamentary_Business/Committees/Senate/Getting_involved |access-date=2024-03-02 |website=Parliament of Australia |language=en-AU |archive-date=2 March 2024 |archive-url=https://web.archive.org/web/20240302224501/https://www.aph.gov.au/Parliamentary_Business/Committees/Senate/Getting_involved |url-status=live }}</ref>

[[File:Senate, Old Parliament House, Canberra.JPG|thumb|The Senate chamber at [[Old Parliament House, Canberra]], where the Parliament met between 1927 and 1988.]]

==Electoral system==
{{see also|Electoral system of Australia}} 
The system for electing senators has changed several times since [[Federation of Australia|Federation]]. The original arrangement involved a [[first-past-the-post voting|first-past-the-post]] and [[Plurality-at-large voting|block voting]] system, on a state-by-state basis. This was replaced in 1919 by [[preferential block voting]]. Block voting tended to produce [[Landslide victory|landslide]] majorities. For instance, from 1920 to 1923 the [[Nationalist Party (Australia)|Nationalist Party]] held all but one of the 36 seats, and from 1947 to 1950, the [[Australian Labor Party]] held all but three.

In 1948, [[single transferable vote]] with [[proportional representation]] on a state-by-state basis became the method for electing senators. At this time the number of senators was expanded from 36 to 60 and it was argued that a move to proportional representation was needed to even up the balance between both major parties in the chamber. The change in voting systems has been described as an "institutional revolution" that has had the effect of limiting the government's ability to control the chamber, as well as helping the rise of Australian minor parties.<ref>{{cite book | author1 = Sawer, Marian | author2 = Miskin, Sarah | name-list-style = amp | title = Papers on Parliament No. 34 Representation and Institutional Change: 50 Years of Proportional Representation in the Senate | publisher = Department of the Senate | year = 1999 | url = https://www.aph.gov.au/binaries/senate/pubs/pops/pop34/pop34.pdf | isbn = 0-642-71061-9 | access-date = 21 September 2020 | archive-date = 3 October 2020 | archive-url = https://web.archive.org/web/20201003050519/https://www.aph.gov.au/binaries/senate/pubs/pops/pop34/pop34.pdf | url-status = live }}</ref><ref name = "electing" />

The [[1984 Australian federal election|1984 election]] saw the introduction of [[group voting tickets in Australia|group ticket voting]], in order to reduce a high rate of informal voting that arose from the requirement that each candidate be given a preference, and to allow small parties and independent candidates a reasonable chance of winning a seat. This allowed voters to select a single party to distribute their preferences on their behalf (voting "above the line"), but voters were still able to vote directly for individual candidates and distribute their own preferences if they wished (voting "below the line") by numbering every box.<ref name="Antony Green">{{cite web |url=https://www.abc.net.au/news/2015-09-23/the-origin-of-senate-group-ticket-voting-and-it-didnt-come-from-/9388658 |title=The Origin of Senate Group Ticket Voting, and it didn't come from the Major Parties |author=[[Antony Green]] |date=23 September 2015 |publisher=ABC |access-date=20 March 2016 |archive-date=24 February 2021 |archive-url=https://web.archive.org/web/20210224224830/https://www.abc.net.au/news/2015-09-23/the-origin-of-senate-group-ticket-voting-and-it-didnt-come-from-/9388658 |url-status=live }}</ref> Following 1981, [[Australian Government|the government]] has only had a majority in the Senate from 2005 to 2007; otherwise, negotiations with other parties and independents have generally been necessary to pass legislation.<ref>{{cite book|last1=Williams|first1=George|last2=Brennan|first2=Sean|last3=Lynch|first3=Andrew|title=Blackshield and Williams Australian constitutional law and theory : commentary and materials|date=2014|publisher=Federation Press|location=Annandale, NSW|isbn=9781862879188|page=415|edition=6th}}</ref>

Group tickets were abolished in advance of the [[2016 Australian federal election|2016 election]] to reduce the number of senators elected with a very small number of first preference votes as a result of the candidates of these micro-parties preferencing each other.<ref name="ABC">{{cite web|url=http://www.abc.net.au/news/2016-04-26/aec-advertising-campaign-on-way-senators-are-elected/7356308|title=Senate voting changes explained in AEC advertisements|date=26 April 2016|website=abc.net.au|access-date=9 August 2018|archive-date=6 May 2016|archive-url=https://webarchive.nla.gov.au/awa/20160506235022/http://pandora.nla.gov.au/pan/158025/20160507-0003/www.abc.net.au/news/2016-04-26/aec-advertising-campaign-on-way-senators-are-elected/7356308.html|url-status=live}}</ref> In the place of group tickets, a form of [[optional preferential voting]] was introduced. As a result of the changes, voters may now assign their preferences for parties above the line (numbering as many boxes as they wish), or individual candidates below the line, and are not required to fill all of the boxes. Both above and below the line voting now use optional preferential voting. For above the line, voters are instructed to number at least their first six preferences; however, a "savings provision" is in place to ensure that ballots will still be counted if less than six are given. For below the line, voters are required to number at least their first 12 preferences. Voters are free to continue numbering as many preferences as they like beyond the minimum number specified. Another savings provision allows ballot papers with at least 6 below the line preferences to be formal. The voting changes make it more difficult for new small parties and independent candidates to be elected to the Senate, but also allow a voter to voluntarily exhaust preferences — that is, to ensure their vote cannot flow to specific candidates or parties — if none of the voter's candidate preferences are elected.<ref>{{cite web |url=https://theconversation.com/explainer-how-does-preferential-voting-work-in-the-senate-116347 |title=Explainer: how does preferential voting work in the Senate? |author=Stephen Morey |date=2 May 2019 |publisher=The Conversation |access-date=27 November 2019}}</ref>

The changes were subject to a challenge in front of [[High Court of Australia]] by sitting South Australian Senator [[Bob Day]] of the [[Family First Party]]. The senator argued that the changes meant the senators would not be "directly chosen by the people" as required by the constitution. The High Court rejected Day's challenge unanimously, deciding that both above the line and below the line voting were consistent with the constitution.<ref>{{cite news |url=https://www.theguardian.com/australia-news/2016/may/13/high-court-rejects-bob-day-appeal-and-finds-senate-voting-changes-are-legal |title=High court rejects Bob Day appeal and finds Senate voting changes are legal |work=[[The Guardian]] |date=13 May 2016}}</ref><ref name=2016DAY>''Day v Australian Electoral Officer for the State of South Australia'' {{Cite AustLII|HCA|20|2016}}</ref>

===Ballot paper===
The Australian Senate voting paper under the single transferable vote proportional representation system resembles the following example (shown in two parts), which shows the candidates for [[Victoria (Australia)|Victorian]] senate representation in the [[2016 Australian federal election|2016 federal election]].

[[File:Victorian-senate-paper-folded-01.png|640x640px|thumb|center|Senate ballot paper used in Victoria for 2016]]

To vote correctly, electors must either:
* Vote for at least six parties above the thick black line, by writing the numbers 1–6 in party boxes. Votes with fewer than six boxes numbered are still admitted to the count through savings provisions.
* Vote for at least twelve candidates below the thick black line, by writing the numbers 1–12 in the individual candidates' boxes. Votes with between six and twelve boxes numbered are still admitted to the count through savings provisions.<ref>{{cite web |url=https://www.aec.gov.au/Voting/How_to_Vote/Voting_Senate.htm |title=Voting in the Senate |date=4 January 2019 |publisher=[[Australian Electoral Commission]] |access-date=27 November 2019 |archive-date=27 February 2020 |archive-url=https://web.archive.org/web/20200227041513/https://aec.gov.au/Voting/How_to_Vote/Voting_Senate.htm |url-status=live }}</ref>

Because each state elects six senators at each half-Senate election, the quota for election is only one-seventh or 14.3% (one third or 33.3% for territories, where only two senators are elected). Once a candidate has been elected with votes reaching the quota amount, any votes they receive in addition to this may be distributed to other candidates as preferences, if there are still open seats to fill.

With an odd number of seats in a half-Senate election (3 or 5), 50.1% of the vote wins a majority (2/3) or (3/5).

With an even number of seats in a half-Senate election (6), 57.1% of the vote is needed to win a majority of seats (4/6).

The ungrouped candidates in the far right column do not have a box above the line. Therefore, they can only get a primary (number 1) vote from electors who vote below the line.  For this reason, some independents register as a group, either with other independents or by themselves, such as group B in the above example.

Names of parties can be shown only if the parties are registered, which requires, among other things, a minimum of 1,500 members.

=== Order of parties ===
The order of parties on the ballot papers and the order of ungrouped candidates are determined by a random ballot conducted by the [[Australian Electoral Commission]].

=== Deposit ===
Candidates, parties and groups pay a deposit of $2,000 per candidate, which is forfeited if they fail to achieve 4% of the primary vote.<ref>{{cite web |url=https://www.aec.gov.au/Elections/candidates/ |title=Candidate information |date=17 October 2019 |publisher=[[Australian Electoral Commission]] |access-date=27 November 2019 |archive-date=19 June 2020 |archive-url=https://web.archive.org/web/20200619202357/https://www.aec.gov.au/Elections/candidates/ |url-status=live }}</ref>

=== Public subsidy ===
Candidates, parties and groups earn a public subsidy if they gain at least 4% of the primary vote.  At the 2019 federal election, funding was $2.756 per formal first preference vote.<ref>{{cite web |url=https://www.aec.gov.au/Parties_and_Representatives/public_funding/index.htm |title=Election funding |date=11 June 2019 |publisher=[[Australian Electoral Commission]] |access-date=27 November 2019 |archive-date=16 October 2019 |archive-url=https://web.archive.org/web/20191016054034/https://www.aec.gov.au/Parties_and_Representatives/public_funding/index.htm |url-status=live }}</ref>

==Membership==
Under sections 7 and 8 of the Australian Constitution:<ref>{{cite web|url=http://www.aph.gov.au/Senate/pubs/odgers/chap0402.htm |title=Chapter 4, Odgers' Australian Senate Practice |publisher=Aph.gov.au |date=2 February 2010 |access-date=17 July 2010 |url-status=dead |archive-url=https://web.archive.org/web/20110321210201/http://www.aph.gov.au/senate/pubs/odgers/chap0402.htm |archive-date=21 March 2011 |df=dmy }}</ref>
* The Senate must comprise an equal number of senators from each original state,
* each original state shall have at least six senators, and
* the Senate must be elected in a way that is not discriminatory among the states.

These conditions have periodically been the source of debate, and within these conditions, the composition and rules of the Senate have varied significantly since federation.

===Size and nexus===
Under [[Section 24 of the Constitution of Australia|Section 24 of the Constitution]], the number of members of the House of Representatives has to be "as nearly as practicable" double the number of senators.

The reasons for the nexus are twofold: a desire to maintain a constant influence for the smaller states, and maintain a constant balance of the two Houses in the event of a joint sitting after a double dissolution. A [[1967 Australian referendum (Parliament)|referendum in 1967]] to eliminate the nexus was rejected.

The size of the Senate has changed over the years. The Constitution originally provided for six senators for each state, resulting in a total of 36 senators.

The Constitution permits the Parliament to increase the number of senators, provided that equal numbers of senators from each original state are maintained; accordingly, in 1948, Senate representation was increased from 6 to 10 senators for each state, increasing the total to 60.

In 1975, the two territories, the [[Northern Territory]] and the [[Australian Capital Territory]], were given an entitlement to elect two senators each for the first time, bringing the number to 64.<ref>{{Cite Legislation AU|Cth|num_act|sota1973408|Senate (Representation of Territories) Act 1973}}</ref> The senators from the Northern Territory also represent constituents from Australia's Indian Ocean Territories ([[Christmas Island]] and the [[Cocos (Keeling) Islands]]), while the senators from the Australian Capital Territory also represent voters from the [[Jervis Bay Territory]] and since 1 July 2016, [[Norfolk Island]].<ref>{{cite web |url=http://www.aec.gov.au/Enrolling_to_vote/special_category/Norfolk_Island_electors.htm |title=Norfolk Island Electors |publisher=Australian Electoral Commission |date=2016 |access-date=6 August 2016 |archive-date=15 June 2016 |archive-url=https://webarchive.nla.gov.au/awa/20160615042855/http://www.aec.gov.au/Enrolling_to_vote/Special_Category/Norfolk_Island_electors.htm |url-status=live }}</ref>

The latest expansion in Senate numbers took place in 1984, when the number of senators from each state was increased from 10 to 12, resulting in a total of 76 senators.<ref name = "electing">Department of the Senate, ''Senate Brief'' No. 1, [http://www.aph.gov.au/Senate/pubs/briefs/brief01.htm 'Electing Australia's Senators'] {{webarchive |url=https://web.archive.org/web/20070829204046/http://www.aph.gov.au/Senate/pubs/briefs/brief01.htm |date=29 August 2007 }}. Retrieved August 2007.</ref>

===Term===
Senators normally serve fixed six-year terms (from 1 July to 30 June). At most federal elections, the seats of 40 of the 76 senators (half of the 72 senators from the six states and all four of the senators from the territories) are contested, along with the entire House of Representatives; such an election is sometimes known as a half-Senate election. The seats of senators representing states elected at a half-Senate election are not contested at the next election, provided it is a half-Senate election. However, under some circumstances, the entire Senate (and the House of Representatives) is dissolved, in what is known as a [[double dissolution]]. Following a double dissolution, half the senators representing states serve terms ending on the third 30 June following the election (two to three years) and the rest serve a five to six-year term. [[Section 13 of the Constitution of Australia#Allocation of terms|Section 13 of the Constitution]] requires the Senate to allocate long and short terms amongst its members. The term of senators representing a territory expires at the same time as there is an election for the House of Representatives.<ref>{{Cite Legislation AU|Cth|act|coaca430|Commonwealth of Australia Constitution Act|13}}</ref>

Section 13 of the Constitution requires that in half-Senate elections, the election of State senators shall take place within one year before the places become vacant. The actual election date is determined by the Governor of each State, who acts on the advice of the State Premier. The Governors almost always act on the recommendation of the Governor-General, with the last independent Senate election writ being issued by the Governor of Queensland during the [[Gair Affair]] in 1974.

Slightly more than half of the Senate is contested at each general election (half of the 72 state senators, and all four of the territory senators), along with the entire House of Representatives. Except in the case of a double dissolution, senators for the states are elected for fixed terms of six years, commencing on 1 July following the election, and ceasing on 30 June six years later.

The term of the four senators from the territories is not fixed, but is defined by the dates of the general elections for the House of Representatives, the period between which can vary greatly, to a maximum of three years and three months. Territory senators commence their terms on the day that they are elected. Their terms expire the day prior to the following general election day.<ref>{{Cite Legislation AU|Cth|num_act|sota1973408|Senate (Representation of Territories) Act 1973|6}}</ref>

While there is no constitutional requirement for the election of senators to take place at the same time as those for members of the House of Representatives, the government usually synchronises the dates of elections for the Senate and House of Representatives. However, because their terms do not coincide, the incoming Parliament may for some time comprise the new House of Representatives and the old Senate, except for the senators representing the territories, until the new senators start their term on the next 1 July.

Following a double dissolution, all 76 senators face re-election. If there is an early House election outside the 12-month period in which Senate elections can occur, the synchronisation of the election will be disrupted, and there can be half-Senate elections without a concurrent House election. The last time this occurred was on [[1970 Australian Senate election|21 November 1970]].

===Quota size===
The number of votes that a candidate must receive to be elected to the senate is referred to as a "quota". The quota is worked out by dividing the number of formal votes by one more than the number of vacancies to be filled and then adding one to the result.<ref>{{Citation |title=The Senate count process |url=https://aec.gov.au/Voting/counting/files/senate-count-process.pdf |type=Pamphlet |archive-url=https://web.archive.org/web/20200325041928/https://aec.gov.au/Voting/counting/files/senate-count-process.pdf |publisher=Australian Electoral Commission |archive-date=25 March 2020}}</ref> The 2019 senate election was a half senate election, so 6 senate vacancies were contested in each state. At this election, the quotas in each state were:
{| class="wikitable"
|-
! State !! 2019 quota !! % of the NSW 2019 quota !! 2016 double dissolution quota<ref>{{Cite web |date=9 August 2016 |title=Senate quota |url=https://results.aec.gov.au/20499/Website/SenateStateProvisionalQuota-20499.htm |url-status=live |archive-url=https://web.archive.org/web/20160921065032/http://results.aec.gov.au/20499/Website/SenateStateProvisionalQuota-20499.htm |archive-date=21 September 2016 |access-date=21 March 2022 |website=Australian Electoral Commission Tally Room – 2016 Federal Election |publisher=Australian Electoral Commission}}</ref>
|-
| NSW || 670,761 || 100% || 345,554
|-
| Vic || 534,207 || 80% || 269,250
|-
| Qld || 414,495 || 62% || 209,475
|-
| WA || 206,661 || 31% || 105,091
|-
| SA || 156,404 || 23% || 81,629
|-
| Tas || 50,285 || 7% || 26,090
|}

===Proportional representation of the states vs one vote one value===
Each state elects the same number of senators, meaning there is equal representation for each of the Australian states, regardless of population, so the Senate, like many upper Houses, does not adhere to the principle of [[one vote one value]]. [[Tasmania]], with a population of around 500,000, elects the same number of senators as [[New South Wales]], which has a population of more than 8 million.

{| class="wikitable"
|-
! State/Territory/Commonwealth !! 2021 Census population<ref>{{Cite web |date=28 June 2022 |title=Population: Census |url=https://www.abs.gov.au/statistics/people/population/population-census/2021 |url-status=live |archive-url=https://web.archive.org/web/20240219235324/https://www.abs.gov.au/statistics/people/population/population-census/latest-release |archive-date=19 February 2024 |access-date=7 March 2024 |website=Australian Bureau of Statistics – Population: Census 2021}}</ref><ref>{{Census 2021 AUS |id=SAL90004 |quick=on |name=Norfolk Island |access-date=7 March 2024}}</ref><ref>{{Census 2021 AUS |id=LGA51710 |name=Christmas Island |quick=on |access-date=7 March 2024}}</ref><ref>{{Census 2021 AUS |id=SAL90003 |name=Jervis Bay |quick=on |access-date=7 March 2024}}</ref><ref>{{Census 2021 AUS |quick=on |id=901021002 |name=Cocos (Keeling) Islands |access-date=7 March 2024}}</ref>!! Population per senator 
|-
| [[New South Wales]] || 8,339,347 || 694,945
|-
| [[Victoria (state)|Victoria]] || 6,503,491 || 541,957
|-
| [[Queensland]] || 5,156,138 || 429,678
|-
| [[Western Australia]] || 2,660,026 || 221,668
|-
| [[South Australia]] || 1,781,516 || 148,459
|-
| [[Tasmania]] || 557,571 || 46,464
|-
| [[Northern Territory]] (including [[Christmas Island]] and [[Cocos (Keeling) Islands]]) || 234,890 || 117,445
|-
| [[Australian Capital Territory]] (including [[Jervis Bay Territory]] and [[Norfolk Island]]) || 456,687 || 228,343
|-
| [[Australia]] || 25,422,788 || 334,510
|}

The proportional election system within each state ensures that the Senate incorporates more political diversity than the lower house ([[Australian House of Representatives|House of Representatives]]), which has historically been a [[Two-party system|two party]] body. The elected membership of the Senate more closely reflects the first voting preference of the electorate as a whole than does the composition of the House of Representatives, despite the large discrepancies from state to state in the ratio of voters to senators.<ref>{{Cite journal|last=Lijphart|first=Arend|date=1 November 1999|title=Australian Democracy: Modifying Majoritarianism?|journal=Australian Journal of Political Science|volume=34|issue=3|pages=313–326|doi=10.1080/10361149950254|issn=1036-1146}}</ref><ref>{{cite conference|url=http://www.aph.gov.au/Senate/pubs/pops/pop34/a01.pdf|title=Overview: Institutional Design and the Role of the Senate|last1=Sawer|first1=Marian|conference=Representation and Institutional Change: 50 Years of Proportional Representation in the Senate|volume=34|editor=Marian Sawer |editor2=Sarah Miskin|date=1999|pages=1–12|archive-url=https://web.archive.org/web/20110117111841/http://aph.gov.au/Senate/pubs/pops/pop34/a01.pdf|archive-date=17 January 2011|url-status=dead|df=dmy-all}}</ref><ref>{{Cite news|url=https://theconversation.com/just-how-representative-are-the-houses-of-parliament-of-how-australians-vote-62160|title=Just how representative are the houses of parliament of how Australians vote?|last=Trudgian|first=Tim|work=The Conversation|access-date=2018-05-30|language=en|archive-date=21 September 2018|archive-url=https://web.archive.org/web/20180921125212/https://theconversation.com/just-how-representative-are-the-houses-of-parliament-of-how-australians-vote-62160|url-status=live}}</ref> This often means that the composition of the Senate is different from that of the House of Representatives, contributing to the Senate's function as a [[Upper house|house of review]].

With proportional representation, and the small majorities in the Senate compared to the generally larger majorities in the House of Representatives, and the requirement that the number of members of the House be "nearly as practicable" twice that of the Senate, a joint sitting after a double dissolution is more likely than not to lead to a victory for the House over the Senate. When the Senate had an odd number of senators retiring at an election (3 or 5), 51% of the vote would lead to a clear majority of 3 out of 5 per state. With an even number of senators retiring at an election, it takes 57% of the vote to win 4 out of 6 seats, which may be insurmountable. This gives the House an advantage in joint sittings but not in ordinary elections, where the Senate may be too evenly balanced to get House legislation through.

A party does not need the support of the Senate to form government (needing only a majority in the House of Representatives), however the Senate can block supply, effectively preventing the government from lawfully spending money. Whether a government facing a Senate that blocks [[Confidence and supply|supply]] is obliged to either resign or call an election was one of the major disputes of the [[1975 Australian constitutional crisis|1975 constitutional crisis]]. However, even where the Senate does not block supply, they can still use their power to frustrate the legislative agenda of the government.

===Parties===
{{see also|Independent politicians in Australia#Senate}}
Political parties have played a major role in the operations of the Senate throughout its history.{{sfn|Bach|2003|p=144}} Some framers of the constitution intended that senators would give first priority to the interests of their states, placing state considerations above party interests. However, others involved in drafting the constitution – including [[Alfred Deakin]], [[Isaac Isaacs]], and [[H. B. Higgins]] – correctly predicted that party considerations would soon dominate state interests.{{sfn|Bach|2003|pp=146–147}}

[[Party discipline]] was important in the Senate from the first parliament, most notably with the formation of an [[Australian Labor Party Caucus|Australian Labor Party caucus]] after the inaugural [[1901 Australian federal election|1901 election]] which required its members to vote in line with decisions of the majority. A two-party system became ensconced in both houses of parliament following the [[Liberal Party (Australia, 1909)|"fusion" of the non-Labor parties]] in 1909, largely as a response to the discipline of the ALP.{{sfn|Bach|2003|p=144-145}} Votes on party lines soon became a regular feature of debate, with corresponding criticisms that the Senate had merely become a rubber stamp for the government rather than filling the role of a states' house.{{sfn|Bach|2003|p=146}}

The "block" voting system used for the Senate prior to electoral reform in 1948 contributed to uneven party representation in the Senate, with the party securing the majority of votes in a state typically winning all that state's Senate seats. After the emergence of the two-party system, there were only two elections between 1910 and 1949 where the government formed in the House of Representatives did not also hold a majority in the Senate. In both cases ([[1913 Australian federal election|1913]] and [[1929 Australian federal election|1929]]) the government lasted only a single term.{{sfn|Bach|2003|p=49}} The system produced "extreme and wildly fluctuating results".{{sfn|Bach|2003|p=75}} On five occasions, the government won all available seats at half-Senate elections; consecutive landslide victories could resulted in the opposition being reduced to a handful of seats, such as when the ALP was reduced to a single Senate seat after the [[1919 Australian federal election|1919 election]].{{sfn|Bach|2003|p=76}} These outcomes, while still uncommon, led the Senate to be perceived as a weak institution serving as a rubber stamp and contributed to calls for reform.{{sfn|Bach|2003|pp=76–77}}

The system of proportional representation passed in 1948 and implemented at the [[1949 Australian federal election|1949 election]] resulted in a more even balance of party representation.{{sfn|Bach|2003|p=78}} A largely unintended consequence of the reforms was the emergence of minor parties as a political force in the Senate, ending a period of 40 years where every elected senator had been a member of either the ALP or the various anti-Labor parties.{{sfn|Bach|2003|p=79}} The first minor party to achieve prominence and obtain the [[Balance of power (parliament)|balance of power]] in the Senate was the [[Democratic Labor Party (Australia, 1955)|Democratic Labor Party]] (DLP), formed after the [[Australian Labor Party split of 1955|ALP split of 1955]].{{sfn|Bach|2003|p=80}} The [[Australian Democrats]] and the [[Australian Greens]] have also held the balance of power at various points.{{sfn|Bach|2003|p=51}} This marked the start of a pattern of non-government control of the Senate, where neither the government nor the opposition held a majority of seats and the government was reliant on minor party and independent senators to pass legislation.{{sfn|Bach|2003|p=52}} Since 1962, the government has secured a Senate majority on only three occasions: after the [[1975 Australian federal election|1975]], [[1977 Australian federal election|1977]] and [[2004 Australian federal election|2004 elections]].<ref>{{cite news |url=https://www.aph.gov.au/binaries/senate/pubs/pops/pop52/23_having_the_numbers_means_not_having_to_explain.pdf |title=Having the Numbers Means Not Having to Explain: The Effect of the Government Majority in the Senate |first=Harry |last=Evans |year=2009 |work=Papers on Parliament |volume=52 |publisher=Parliament of Australia |pages=151–1633}}</ref>

===Casual vacancies===
{{see also|Casual vacancies in the Australian Parliament|List of Australian Senate appointments}}
Section 15 of the Constitution provides that a [[Casual vacancies in the Australian Parliament|casual vacancy]] of a State senator shall be filled by the State Parliament.<ref>{{Cite Legislation AU|Cth|act|coaca430|Commonwealth of Australia Constitution Act|15}}</ref> If the previous senator was a member of a particular political party the replacement must come from the same party, but the State Parliament may choose not to fill the vacancy, in which case Section 11 requires the Senate to proceed regardless. If the State Parliament happens to be in recess when the vacancy occurs, the Constitution provides that the State Governor can appoint someone to fill the place until fourteen days after the State Parliament resumes sitting.<ref>{{Cite Legislation AU|Cth|act|coaca430|Commonwealth of Australia Constitution Act|11}}</ref>

== Procedure ==
[[File:Senate panorama.jpg|thumb|upright=1.9|The Australian Senate]]

=== Work ===
The Australian Senate typically sits for 50 to 60 days a year.{{efn|Figures are available for each year on the Senate StatsNet.}} Most of those days are grouped into 'sitting fortnights' of two four-day weeks. These are in turn arranged in three periods: the autumn sittings, from February to April; the winter sittings, which commence with the delivery of the budget in the House of Representatives on the first sitting day of May and run through to June or July; and the spring sittings, which commence around August and continue until December, and which typically contain the largest number of the year's sitting days.

The senate has a regular schedule that structures its typical working week.<ref>{{cite web |url=http://www.aph.gov.au/Senate/work/routineofbus.htm |title=Senate weekly routine of business |author=<!--Staff writer(s); no by-line.--> |date=7 November 2011 |publisher=Australian Senate |archive-url=https://web.archive.org/web/20120126125039/http://www.aph.gov.au/Senate/work/routineofbus.htm |archive-date=26 January 2012}}</ref>

====Dealing with legislation====
All [[bill (law)|bills]] must be passed by a majority in both the House of Representatives and the Senate before they become law. Most bills originate in the House of Representatives, and the great majority are introduced by the government.

The usual procedure is for notice to be given by a government minister the day before the bill is introduced into the Senate. Once introduced the bill goes through several stages of consideration. It is given a [[reading (legislature)|first reading]], which represents the bill's formal introduction into the chamber.

<blockquote>The first reading is followed by debate on the principle or policy of the bill (the second reading debate). Agreement to the bill in principle is indicated by a second reading, after which the detailed provisions of the bill are considered by one of a number of methods (see below). Bills may also be referred by either House to their specialised standing or select committees. Agreement to the policy and the details is confirmed by a third and final reading. These processes ensure that a bill is systematically considered before being agreed to.<ref>Australian Senate, [http://www.aph.gov.au/Senate/pubs/briefs/brief08.htm 'The Senate and Legislation'] {{webarchive |url=https://web.archive.org/web/20080924114919/http://www.aph.gov.au/Senate/pubs/briefs/brief08.htm |date=24 September 2008 }}, ''Senate Brief'', No. 8, 2008, Department of the Senate, Canberra.</ref></blockquote>
The Senate has detailed rules in its standing orders that govern how a bill is considered at each stage.<ref>Australian Senate, [http://www.aph.gov.au/Senate/pubs/guides/briefno09.htm 'Consideration of legislation'] {{webarchive|url=https://web.archive.org/web/20080926083250/http://www.aph.gov.au/Senate/pubs/guides/briefno09.htm |date=26 September 2008 }}, ''Brief Guides to Senate Procedure'', No. 9, Department of the Senate, Canberra.</ref> This process of consideration can vary greatly in the amount of time taken. Consideration of some bills is completed in a single day, while complex or controversial legislation may take months to pass through all stages of Senate scrutiny. The Constitution provides that if the Senate vote is equal, the question shall pass in the negative.<ref name="Con23">{{Cite Legislation AU|Cth|act|coaca430|Commonwealth of Australia Constitution Act|23}}</ref>

====Committees====
{{Main|Australian Senate committees}}
[[Image:AustralianSenateCommitteeRm.JPG|thumb|alt=A meeting room containing a large horseshoe-shaped desk, with red leather office chairs surrounding its outside edge, a microphone mounted in the desk in front of each chair|A Senate committee room in Parliament House, Canberra]]
[[File:Australian Parliament Parliamentary Committees.webm|thumb|left|A short video on Australian Parliamentary Committees]]
In addition to the work of the main chamber, the Senate also has a large number of [[Australian Senate committees|committees]] which deal with matters referred to them by the Senate. These committees also conduct hearings three times a year in which the government's budget and operations are examined. These are known as estimates hearings. Traditionally dominated by scrutiny of government activities by non-government senators, they provide the opportunity for all senators to ask questions of ministers and public officials. This may occasionally include government senators examining activities of independent publicly funded bodies, or pursuing issues arising from previous governments' terms of office. There is however a convention that senators do not have access to the files and records of previous governments when there has been an election resulting in a change in the party in government. Once a particular inquiry is completed the members of the committee can then produce a report, to be tabled in Parliament, outlining what they have discovered as well as any recommendations that they have produced for the Government to consider.<ref name = "odgcom">{{cite web |url=http://www.aph.gov.au/About_Parliament/Senate/Powers_practice_n_procedures/Odgers_Australian_Senate_Practice/Chapter_16 |title=Odgers' Australian Senate Practice Fourteenth Edition Chapter 16 – Committees |date=2017 |access-date=19 March 2017 |archive-date=20 March 2017 |archive-url=https://web.archive.org/web/20170320052009/http://www.aph.gov.au/About_Parliament/Senate/Powers_practice_n_procedures/Odgers_Australian_Senate_Practice/Chapter_16 |url-status=live }}</ref>

The ability of the Houses of Parliament to establish committees is referenced in Section 49 of the Constitution, which states, "The powers, privileges, and immunities of the Senate and of the House of Representatives, and of the members and the committees of each House, shall be such as are declared by the Parliament, and until declared shall be those of the Commons House of Parliament of the United Kingdom, and of its members and committees, at the establishment of the Commonwealth."<ref name="con49">{{Cite Legislation AU|Cth|act|coaca430|Commonwealth of Australia Constitution Act|49}}</ref><ref name = "odgcom"/>

Parliamentary committees can be given a wide range of powers. One of the most significant powers is the ability to summon people to attend hearings in order to give evidence and submit documents. Anyone who attempts to hinder the work of a Parliamentary committee may be found to be in [[contempt of Parliament]]. There are a number of ways that witnesses can be found in contempt, these include; refusing to appear before a committee when summoned, refusing to answer a question during a hearing or to produce a document, or later being found to have lied to or misled a committee. Anyone who attempts to influence a witness may also be found in contempt.<ref name="com">{{cite web |url=http://www.aph.gov.au/About_Parliament/House_of_Representatives/Powers_practice_and_procedure/00_-_Infosheets/Infosheet_4_-_Committees |title=Infosheet 4 – Committees |publisher=aph.gov.au |access-date=22 February 2017 |archive-date=17 October 2016 |archive-url=https://webarchive.nla.gov.au/awa/20161017121253/http://www.aph.gov.au/About_Parliament/House_of_Representatives/Powers_practice_and_procedure/00_-_Infosheets/Infosheet_4_-_Committees |url-status=live }}</ref> Other powers include the ability to meet throughout Australia, to establish subcommittees and to take evidence in both public and private hearings.<ref name = "odgcom"/>

Proceedings of committees are considered to have the same legal standing as proceedings of Parliament. They are recorded by [[Hansard]], except for private hearings, and also operate under [[Parliamentary privilege]]. Every participant, including committee members and witnesses giving evidence, is protected from being prosecuted under any civil or criminal action for anything they may say during a hearing. Written evidence and documents received by a committee are also protected.<ref name="com"/><ref name = "odgcom"/>

====Holding governments to account====
One of the functions of the Senate, both directly and through its [[Australian Senate committees|committees]], is to scrutinise government activity. The vigour of this scrutiny has been fuelled for many years by the fact that the party in government has seldom had a majority in the Senate. Whereas in the House of Representatives the government's majority has sometimes limited that chamber's capacity to implement executive scrutiny, the opposition and minor parties have been able to use their Senate numbers as a basis for conducting inquiries into government operations. When the [[Howard government]] won control of the Senate in 2005, it sparked a debate about the effectiveness of the Senate in holding the government of the day accountable for its actions. Government members argued that the Senate continued to be a forum of vigorous debate, and its committees continued to be active.<ref>{{cite web |url=http://www.financeminister.gov.au/media/2006/mr_432006.html |title=Media Release 43/2006 – Senate remains robust under Government majority |author=<!--Staff writer(s); no by-line.--> |date=30 June 2006 |archive-url=https://web.archive.org/web/20070927145249/http://www.financeminister.gov.au/media/2006/mr_432006.html |archive-date=27 September 2007}}</ref> The Opposition leader in the Senate suggested that the government had attenuated the scrutinising activities of the Senate.<ref>{{cite web |url=http://www.chrisevans.alp.org.au/news/1105/senatespeeches10-01.php |title=Senator Chris Evans, The tyranny of the majority (speech) |author=<!--Staff writer(s); no by-line.--> |date=10 November 2005 |quote="Labor has accused the Government of 'ramming' bills through the Senate – but Labor "guillotined" Parliamentary debate more than twice the number of times in their 13 years in Government than the Coalition has over the last decade. In the last six months, the Government has not sought to guillotine any bill through the Senate." |archive-url=https://web.archive.org/web/20091112013742/http://www.chrisevans.alp.org.au/news/1105/senatespeeches10-01.php |archive-date=12 November 2009}}</ref> The [[Australian Democrats]], a minor party which frequently played mediating and negotiating roles in the Senate, expressed concern about a diminished role for the Senate's committees.<ref>{{cite web |url=http://www.democrats.org.au/docs/2006/PR_Senate_Attack_Accountability.pdf |title=Senator Andrew Murray: Australian Democrats Accountability Spokesperson Senate Statistics 1 July 2005 – 30 June 2006 |author=<!--Staff writer(s); no by-line.--> |date=4 July 2006 |archive-url=https://web.archive.org/web/20060805200949/http://www.democrats.org.au/docs/2006/PR_Senate_Attack_Accountability.pdf |archive-date=5 August 2006}}</ref>

In addition to review of legislation, the ''Legislation Act 2003'' provides that the Senate may also disallow legislative instruments – typically regulations made by government ministers using powers delegated by relevant legislation. The same power is afforded to the House of Representatives, but is rarely exercised given the government's control of numbers in the lower house. The ''Legislation Act 2003'' provides that any senator may move a motion disallowing a legislative instrument, which if passed within 15 days has the effect of repealing the instrument. The government may not enact an equivalent legislative instrument for a period of six months following the disallowal.<ref>{{cite news|url=https://www.aph.gov.au/about_parliament/senate/powers_practice_n_procedures/brief_guides_to_senate_procedure/no_19|title=No. 19 – Disallowance|work=Guides to Senate Procedure|publisher=Parliament of Australia|access-date=19 May 2024|archive-date=19 May 2024|archive-url=https://web.archive.org/web/20240519071937/https://www.aph.gov.au/about_parliament/senate/powers_practice_n_procedures/brief_guides_to_senate_procedure/no_19|url-status=live}}</ref>

===Voting===
Senators are called upon to vote on matters before the Senate. These votes are called ''divisions'' in the case of Senate business, or ''ballots'' where the vote is to choose a senator to fill an office of the Senate (such as the [[President of the Senate (Australia)|President]]).<ref>''Senate Standing Orders'', numbers 7, 10, 98–105, 163</ref>

Party discipline in [[Politics of Australia|Australian politics]] is strong, so divisions almost always are decided on party lines. Nevertheless, the existence of minor parties holding the balance of power in the Senate has made divisions in that chamber more uncertain than in the House of Representatives.

When a division is to be held, bells ring throughout the parliament building for four minutes, during which time senators must go to the chamber. At the end of that period the doors are locked and a vote is taken, by identifying and counting senators according to the side of the chamber on which they sit (ayes to the right of the chair, noes to the left). The whole procedure takes around eight minutes. Senators with commitments that keep them from the chamber may make arrangements in advance to be 'paired' with a senator of the opposite political party, so that their absence does not affect the outcome of the vote.

The Senate contains an even number of senators, so a tied vote is a real prospect (which regularly occurs when the party numbers in the chamber are finely balanced). [[Section 23 of the Constitution of Australia|Section 23 of the Constitution]] requires that in the event of a tied division, the question is resolved in the negative. The system is however different for ballots for offices such as the President. If such a ballot is tied, the [[Clerk of the Australian Senate|Clerk of the Senate]] decides the outcome by the drawing of lots. In reality, conventions govern most ballots, so this situation does not arise.<ref name="Con23"/>

====Political parties and voting outcomes====
The strength of party discipline is demonstrated by how rare it is for members to vote against the position taken by their party. The exceptions are where a [[conscience vote]] is allowed by one or more of the political parties; and occasions where a member of a political party [[crossing the floor|crosses the floor]] of the chamber to vote against the instructions of their [[whip (politics)|party whip]]. Crossing the floor very rarely occurs, but is more likely in the Senate than in the House of Representatives.<ref>Deirdre McKeown, Rob Lundie and Greg Baker, [http://www.aph.gov.au/library/pubs/rn/2005-06/06rn11.pdf 'Crossing the floor in the Federal Parliament 1950 – August 2004'] {{webarchive |url=https://web.archive.org/web/20081003132418/http://www.aph.gov.au/library/pubs/rn/2005-06/06rn11.pdf |date=3 October 2008 }}, ''Research Note'', No. 11, 2005–06, Department of Parliamentary Services, Canberra.</ref>

When the government has a majority in the Senate, the importance of party discipline increases, as it is only backbenchers that may prevent the passage of government bills. While strong party discipline has been a feature of Australian politics since the emergence of the Labor Party in the early 1900s, as late as 1980 the Fraser government could not be assured that his party's majority in the Senate would translate to absolute control, with at least 12 senators prepared to vote against the government.<ref>{{Cite book |last=Evans |first=Harry |title=Restraining elective dictatorship: the upper house solution? |date=2008 |publisher=University of Western Australia Press |isbn=978-1-921401-09-1 |editor-last=Aroney |editor-first=Nicholas |location=Crawley, W.A |page=71 |language=en |chapter=The case for bicameralism |editor-last2=Prasser |editor-first2=Scott |editor-last3=Nethercote |editor-first3=J. R.}}</ref> Similarly, when the Howard government had a Senate majority between 2005 and 2007, the internal differences between members of the government coalition parties became more apparent.<ref>{{cite web |url=http://democratic.audit.anu.edu.au/papers/20050630_uhr.pdf |title=How Democratic is Parliament? A case study in auditing the performance of Parliaments |last=Uhr |first=John |date=June 2005 |publisher=Democratic Audit of Australia, Discussion Paper |archive-url=https://web.archive.org/web/20130514151348/http://democratic.audit.anu.edu.au/papers/20050630_uhr.pdf |archive-date=14 May 2013}}</ref> However, due to the increase in party discipline, only two senators in this period crossed the floor:<ref>Peter Veness, [https://archive.today/20070728091913/http://www.news.com.au/story/0,10117,19479942-29277,00.html 'Crossing floor 'courageous, futile'], news.com.au, 15 June 2006. Retrieved January 2008.</ref> [[Gary Humphries]] on civil unions in the Australian Capital Territory, and [[Barnaby Joyce]] on [[voluntary student unionism]].<ref>Neither of these instances resulted in the defeat of a government proposal, as in both cases Senator [[Steve Fielding]] voted with the government.</ref> A more significant potential instance of floor crossing was averted when the government withdrew its Migration Amendment (Designated Unauthorised Arrivals) Bill, of which several government senators had been critical, and which would have been defeated had it proceeded to the vote.<ref>{{cite web |last=Howard |first=John |date=14 August 2006 |title=Transcript of the Prime Minister the Hon John Howard MP Press Conference, Parliament House, Canberra |url=http://www.pm.gov.au/news/interviews/Interview2073.html |url-status=dead |archive-url=https://web.archive.org/web/20060821014554/http://www.pm.gov.au/news/interviews/Interview2073.html |archive-date=21 August 2006 |access-date=21 August 2006 |website=Prime Minister of Australia News Room |publisher=Office of the Prime Minister of the Commonwealth of Australia}}</ref> The controversy that surrounded these examples demonstrated both the importance of [[backbencher]]s in party policy deliberations and the limitations to their power to influence outcomes in the Senate chamber.

In September 2008, Barnaby Joyce became leader of the Nationals in the Senate, and stated that his party in the upper house would no longer necessarily vote with their Liberal counterparts.<ref>{{cite web |url=http://news.smh.com.au/national/nationals-wont-toe-libs-line-joyce-20080918-4isw.html |title=Nationals won't toe Libs' line: Joyce – SMH 18/9/2008 |publisher=News.smh.com.au |date=18 September 2008 |access-date=17 July 2010 |archive-date=3 December 2013 |archive-url=https://web.archive.org/web/20131203102843/http://news.smh.com.au/national/nationals-wont-toe-libs-line-joyce-20080918-4isw.html |url-status=live }}</ref>

== Where the Houses disagree ==
=== Double dissolutions and joint sittings ===
If the Senate rejects or fails to pass a proposed law, or passes it with amendments to which the House of Representatives will not agree, and if after an interval of three months the Senate refuses to pass the same piece of legislation, the government may either abandon the bill or continue to revise it, or, in certain circumstances outlined in section 57 of the [[Constitution of Australia|Constitution]], the Prime Minister can advise the Governor-General to dissolve the entire parliament in a [[double dissolution]]. In such an event, the entirety of the Senate faces re-election, as does the House of Representatives, rather than only about half the chamber as is normally the case. After a double dissolution election, if the bills in question are reintroduced, and if they again fail to pass the Senate, the Governor-General may agree to a ''joint sitting'' of the two Houses in an attempt to pass the bills. [[Joint Sitting of the Australian Parliament of 1974|Such a sitting]] has only occurred once, in 1974.<ref>{{Cite Legislation AU|Cth|act|coaca430|Commonwealth of Australia Constitution Act|57}}</ref>

The double dissolution mechanism is not available for bills that originate in the Senate and are blocked in the lower house.

On 8 October 2003, the then Prime Minister [[John Howard]] initiated public discussion of whether the mechanism for the resolution of deadlocks between the Houses should be reformed. High levels of support for the existing mechanism, and a very low level of public interest in that discussion, resulted in the abandonment of these proposals.<ref>{{cite web
| url         = http://dpmc.gov.au/conschange/report/docs/report.pdf
| archive-url = https://webarchive.nla.gov.au/awa/20080117110700/http://pandora.nla.gov.au/pan/79623/20080117-2207/dpmc.gov.au/conschange/report/docs/report.pdf
| url-status  = dead
| archive-date = 2008-01-17
| title       = Resolving Deadlocks: The Public Response
| author      = Consultative Group on Constitutional Change
| date        = March 2004
| page        = 8
}}{{cbignore|bot=medic}}
</ref>

=== Allocating terms after a double dissolution ===

After a double dissolution election, section 13 of the Constitution requires the Senate to divide the senators into two classes, with the first class having a three-year "short term", and the second class a six-year "long term". The Senate may adopt any approach it wants to determine how to allocate the long and short terms, however two methods are currently 'on the table':
* "elected-order" method, where the senators elected first attain a six-year term. This approach tends to favour minor party candidates as it gives greater weight to their first preference votes;<ref name="whichones">{{cite web
| url         = http://www.abc.net.au/news/2016-07-05/election-2016-new-senate-terms-explained/7571406
| title       = Election 2016: How do we decide which senators are in for three years and which are in for six?
| author      = Uma Patel
| publisher   = Australian Broadcasting Corporation
| date        = 6 July 2016}}</ref> or
* re-count method, where the long terms are allocated to those senators who would have been elected first if the election had been a standard half-Senate election.<ref name="longnshort">{{cite web
| url         = http://blogs.abc.net.au/antonygreen/2016/04/how-long-and-short-terms-are-allocated-after-a-double-dissolution.html
| url-status = dead
| archive-url = https://web.archive.org/web/20160626235215/http://blogs.abc.net.au/antonygreen/2016/04/how-long-and-short-terms-are-allocated-after-a-double-dissolution.html
| archive-date = 26 June 2016
| title       = How Long and Short Senate Terms are Allocated After a Double Dissolution
| author      = [[Antony Green]]
| publisher   = Australian Broadcasting Corporation
| date        = 25 April 2016}}</ref> This method is likely to be preferred by the major parties in the Senate where it would deliver more six-year terms to their members.<ref name=whichones />

The Senate applied the "elected-order" method following the [[1987 Australian federal election|1987 double dissolution election]].<ref name=longnshort /> Since that time the Senate has passed resolutions on several occasions indicating its intention to use the re-count method to allocate seats at any future double dissolution, which [[Antony Green|Green]] describes as a fairer approach but notes could be ignored if a majority of senators opted for the "elected-order" method instead.<ref name=longnshort /> In both double dissolution elections since 1987, the "elected order" method was used.

==Blocking supply==
{{Further|1975 Australian constitutional crisis}}
The Senate has the same legislative power as the House of Representatives, except it may not originate or amend taxing or appropriation bills; they may only pass or reject them. The ability to block the annual appropriations bills required to fund the government ("supply") was exercised in the [[1975 Australian constitutional crisis]]. During the crisis, the [[Opposition (Australia)|Opposition]] used its numbers in the Senate to defer supply bills, refusing to deal with them until an election was called for both Houses of Parliament, an election which it hoped to win. The [[Prime Minister of Australia|Prime Minister]] of the day, [[Gough Whitlam]], contested the legitimacy of the blocking and refused to resign. The crisis brought to a head two Westminster conventions that, under the Australian constitutional system, were in conflict – firstly, that a government may continue to govern for as long as it has the support of the [[lower house]], and secondly, that a government that no longer has access to supply must either resign or be dismissed. The deadlock ended in November 1975 when Governor-General [[John Kerr (governor-general)|Sir John Kerr]] dismissed Whitlam's government and appointed Opposition Leader [[Malcolm Fraser|Fraser]] as Prime Minister, on the condition that elections for both Houses of parliament be held.<ref name=kerr>{{cite web|last1=Kerr|first1=John|title=Statement from John Kerr (dated 11 November 1975) explaining his decisions.|url=http://whitlamdismissal.com/documents/kerr-statement.shtml|website=WhitlamDismissal.com|access-date=11 January 2017|archive-url=https://web.archive.org/web/20120223060041/http://whitlamdismissal.com/documents/kerr-statement.shtml|archive-date=23 February 2012|url-status=dead}}</ref>

In 2014, [[Australian Broadcasting Corporation|ABC]] elections analyst Antony Green noted that the blocking of supply alone cannot force a double dissolution. There must be legislation repeatedly blocked by the Senate which the government can then choose to use as a trigger for a double dissolution.<ref>{{cite news|last1=Green|first1=Antony|title=An Early Double Dissolution? Don't Hold Your Breath!|url=https://www.abc.net.au/news/2014-05-19/an-early-double-dissolution-dont-hold-your-breath/9388414|archive-date=13 September 2024|archive-url=https://web.archive.org/web/20240913100304/https://www.abc.net.au/news/2014-05-19/an-early-double-dissolution-dont-hold-your-breath/9388414|url-status=live|newspaper=[[ABC News (Australia)|ABC News]]|date=19 May 2014|access-date=1 August 2016}}</ref>

==Current Senate==
{{See also|Members of the Australian Senate, 2025-2028}}

{| class="wikitable"
|-
! State
! colspan=12| Seats held
|-
|| [[List of senators from New South Wales|New South Wales]]
| width=20 {{Australian party style|Greens}} |
| width=20 {{Australian party style|Greens}} | 
| width=20 {{Australian party style|Labor}} | 
| width=20 {{Australian party style|Labor}} | 
| width=20 {{Australian party style|Labor}} | 
| width=20 {{Australian party style|Labor}} | 
| width=20 {{Australian party style|Liberal}} | 
| width=20 {{Australian party style|Liberal}} | 
| width=20 {{Australian party style|Liberal}} | 
| width=20 {{Australian party style|Liberal}} | 
| width=20 {{Australian party style|National}} | 
| width=20 {{Australian party style|One Nation}} | 
|-
|| [[List of senators from Victoria|Victoria]]
| width=20 {{Australian party style|Greens}} | 
| width=20 {{Australian party style|Labor}} | 
| width=20 {{Australian party style|Labor}} | 
| width=20 {{Australian party style|Labor}} | 
| width=20 {{Australian party style|Labor}} |
| width=20 {{Australian party style|Labor}} | 
| width=20 {{Australian party style|Independent}} | 
| width=20 {{Australian party style|Liberal}} | 
| width=20 {{Australian party style|Liberal}} | 
| width=20 {{Australian party style|Liberal}} | 
| width=20 {{Australian party style|National}} | 
| width=20 {{Australian party style|United Australia Party (current)}} | 
|-
|| [[List of senators from Queensland|Queensland]]
| width=20 {{Australian party style|Greens}} | 
| width=20 {{Australian party style|Greens}} | 
| width=20 {{Australian party style|Labor}} | 
| width=20 {{Australian party style|Labor}} | 
| width=20 {{Australian party style|Labor}} | 
| width=20 {{Australian party style|Labor}} | 
| width=20 {{Australian party style|Liberal}} | 
| width=20 {{Australian party style|Liberal}} | 
| width=20 {{Australian party style|National}} | 
| width=20 {{Australian party style|National}} | 
| width=20 {{Australian party style|One Nation}} | 
| width=20 {{Australian party style|One Nation}} | 
|-
|| [[List of senators from Western Australia|Western Australia]]
| width=20 {{Australian party style|Greens}} | 
| width=20 {{Australian party style|Labor}} | 
| width=20 {{Australian party style|Labor}} | 
| width=20 {{Australian party style|Labor}} | 
| width=20 {{Australian party style|Labor}} | 
| width=20 {{Australian party style|Labor}} | 
| width=20 {{Australian party style|Australia's Voice}} |
| width=20 {{Australian party style|Liberal}} | 
| width=20 {{Australian party style|Liberal}} | 
| width=20 {{Australian party style|Liberal}} | 
| width=20 {{Australian party style|Liberal}} | 
| width=20 {{Australian party style|One Nation}} | 
|-
|| [[List of senators from South Australia|South Australia]]
| width=20 {{Australian party style|Greens}} | 
| width=20 {{Australian party style|Greens}} | 
| width=20 {{Australian party style|Labor}} | 
| width=20 {{Australian party style|Labor}} | 
| width=20 {{Australian party style|Labor}} | 
| width=20 {{Australian party style|Labor}} | 
| width=20 {{Australian party style|Labor}} | 
| width=20 {{Australian party style|Liberal}} | 
| width=20 {{Australian party style|Liberal}} | 
| width=20 {{Australian party style|Liberal}} | 
| width=20 {{Australian party style|Liberal}} | 
| width=20 {{Australian party style|Liberal}} | 
|-
|| [[List of senators from Tasmania|Tasmania]]
| width=20 {{Australian party style|Greens}} | 
| width=20 {{Australian party style|Greens}} | 
| width=20 {{Australian party style|Labor}} | 
| width=20 {{Australian party style|Labor}} | 
| width=20 {{Australian party style|Labor}} | 
| width=20 {{Australian party style|Labor}} | 
| width=20 {{Australian party style|Jacqui Lambie Network}} | 
| width=20 {{Australian party style|Independent}} | 
| width=20 {{Australian party style|Liberal}} | 
| width=20 {{Australian party style|Liberal}} | 
| width=20 {{Australian party style|Liberal}} | 
| width=20 {{Australian party style|Liberal}} | 
|-
|| [[List of senators from the Australian Capital Territory|Australian Capital Territory]]
| width=20 {{Australian party style|Labor}} | 
| width=20 {{Australian party style|Independent}} | 
|-
|| [[List of senators from the Northern Territory (Australia)|Northern Territory]]
| width=20 {{Australian party style|Labor}} |
| width=20 {{Australian party style|Liberal}} | 
|-
|}

=== 2022 election ===
{{See also|Results of the 2022 Australian federal election (Senate)}}
In the 2022 half-Senate election, 40 seats were up for election: six from each state and two from each territory. The senate results were: Liberal/National [[Coalition (Australia)|coalition]] 15 seats (−4), Labor 15 seats (±0), Greens 6 seats (+3), Jacqui Lambie Network 1 seat (+1), One Nation 1 seat (±0), [[United Australia Party (2013)|United Australia]] 1 seat (+1), and [[Independent politician|independent]] 1 seat (+1). The composition of the Senate after the election was:

*[[Liberal Party of Australia|Liberal]]/[[National Party of Australia|National]] [[Coalition (Australia)|Coalition]] 32 seats
*[[Australian Labor Party|Labor]] 26 seats
*[[Australian Greens|Greens]] 12 seats
*[[Jacqui Lambie Network]] 2 seats
*[[Pauline Hanson's One Nation|One Nation]] 2 seats
*[[United Australia Party (2013)|United Australia]] 1 seat
*Independent ([[David Pocock]]) 1 seat

=== 2025 election ===
{{See also|Results of the 2025 Australian federal election (Senate)}}
In the 2025 half-senate election, 40 seats were up for election: six from each state and two from each territory. The senate results were: Liberal/National [[coalition]] 13 seats (−3), Labor 16 seats (+3) Greens 6 seats (±0), One Nation 3 seats (+2),  [[Jacqui Lambie Network]] (±0), and Independent (±0). Following the election, senator [[Dorinda Cox]] switched from Greens to Labor.<ref>{{Cite web | url = https://www.abc.net.au/news/2025-06-04/greens-investigation-dorinda-cox-over/105377608 | title = Greens internal investigation into Dorinda Cox over now she's left the party | work = ABC News | date = 4 June 2025 | agency = [[Australian Broadcasting Corporation]]}}</ref><ref>{{Cite web | url = https://www.aph.gov.au/Senators_and_Members/Senators/Senate_composition | title = Senate composition | date = 1 July 2025 | agency = [[Parliament of Australia]]}}</ref> The composition of the Senate after the election was: 

*[[Australian Labor Party|Labor]]: 29 seats
* [[Liberal Party of Australia|Liberal]]/[[National Party of Australia|National]] [[Coalition (Australia)|Coalition]]: 27 seats
* [[Australian Greens|Greens]] 10 seats
* [[Pauline Hanson's One Nation|One Nation]]: 4 seats
* [[United Australia Party (2013)|United Australia]]: 1 seat
* [[Jacqui Lambie Network]]: 1 seat
* [[Australia's Voice]]: 1 seat
* Independent: 3 seats

==Historical party composition of the Senate==
{{Excerpt|Parliament of Australia|Senate compositions}}
==See also==
* [[2025 Australian federal election]]
* [[Canberra Press Gallery]]
* [[Clerk of the Australian Senate]]
* [[Double dissolution]]
* [[Father of the Australian Senate]]
* [[List of Australian Senate appointments]]
* [[Members of the Australian Parliament who have served for at least 30 years]]
* [[Members of the Australian Senate, 2025–2028]]
* [[Women in the Australian Senate]]

==Notes==
{{notelist}}

==References==
{{reflist|30em}}

== Further reading ==
{{Refbegin}}
* {{Cite book |last1=Odgers |first1=JR |url=https://www.aph.gov.au/About_Parliament/Senate/Powers_practice_n_procedures/Odgers_Australian_Senate_Practice |title=Odgers' Australian Senate Practice |last2=Evans |first2=Henry |date=30 June 2022 |publisher=Department of the Senate |isbn=978-1-76010-503-7 |editor-last=Laing |editor-first=Rosemary |edition=14th with updates to 30 June 2022 |location=Canberra |language=en-AU }}
* {{cite book| last = Bach| first = Stanley| title = Platypus and Parliament: The Australian Senate in Theory and Practice| publisher = Department of the Senate| year = 2003| url = http://www.aph.gov.au/About_Parliament/Senate/Powers_practice_n_procedures/platparl| isbn = 978-0-642-71291-2| access-date = 13 December 2016| archive-date = 20 December 2016| archive-url = https://web.archive.org/web/20161220144354/http://www.aph.gov.au/About_Parliament/Senate/Powers_practice_n_procedures/platparl| url-status = live}}
* John Halligan, Robin Miller and John Power, ''Parliament in the Twenty-first Century: Institutional Reform and Emerging Roles'', Melbourne University Publishing, 2007
* {{cite book | author1 = Sawer, Marian | author2 = Miskin, Sarah | name-list-style = amp | title = Papers on Parliament No. 34 Representation and Institutional Change: 50 Years of Proportional Representation in the Senate | publisher = Department of the Senate | year = 1999 | url = https://www.aph.gov.au/binaries/senate/pubs/pops/pop34/pop34.pdf | isbn = 0-642-71061-9 | access-date = 21 September 2020 | archive-date = 3 October 2020 | archive-url = https://web.archive.org/web/20201003050519/https://www.aph.gov.au/binaries/senate/pubs/pops/pop34/pop34.pdf | url-status = live }}
{{Refend}}

== External links ==
{{Library resources box|by=no|onlinebooks=no|about=yes|wikititle=Australian senate}}
* {{Official website|http://www.aph.gov.au/About_Parliament/Senate|Official website of the Australian Senate}}
* [http://www.aph.gov.au/News_and_Events/Watch_Parliament Australian Parliament – live broadcasting]
* [http://www.aph.gov.au/Parliamentary_Business/Statistics/Senate_StatsNet Senate StatsNet]
* [http://biography.senate.gov.au/ The Biographical Dictionary of the Australian Senate]
* [https://www.abc.net.au/radionational/programs/rearvision/australias-upper-houses/11038996 Australia's Upper Houses – ABC Rear Vision] A podcast about the development of Australia's upper houses into STV proportional representation elected chambers.

{{Electoral results for the Australian Senate}}
{{Australian Senate Delegations}}
{{Australian political parties}}
{{National upper houses}}
{{Parliament of Australia}}
{{Parliaments of Australia}}
{{Politics of Australia}}
{{Coord|35|18|28|S|149|07|26|E|display=title}}

[[Category:Australian Senate| ]]
[[Category:1901 establishments in Australia]]
[[Category:National upper houses|Australia]]
[[Category:Parliament of Australia|Senate, Australian]]
[[Category:Politics of Australia|Senate, Australian]]
[[Category:Westminster system]]
[[Category:1975 Australian constitutional crisis]]
[[Category:Federal chambers]]