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Musical chairs in parliament: Does Lidia Thorpe's senate seat belong to her or The Greens?

The now-independent will be in the senate until her term expires in 2028.

Politicians changing parties during their term in Parliament is nothing new. In the House of Representatives, it is accepted that when a politician leaves a party and either joins a different party or sits as an independent, they get to keep their seat until the next election. But in the Senate, things don’t seem as simple. So when Lidia Thorpe, Greens Senator for Victoria, quit her party, who owns that seat in the Senate: the Greens or Senator Thorpe? To answer this question we have to travel back to the 1780s.

When Chapter I of the Australian Constitution was being written in the 1890s, it was decided that Parliament would be based on the United States Congress and the United States Constitution. This meant that the Australian House of Representatives would consist of MPs representing electorates. Electorates were based on population size, meaning that the more populous states would have more MPs. In Australia, this benefited Victoria and New South Wales.

However, as in the US, it was decided that each state would have an equal number of Senators, to represent the interests of the less populous states. The only important difference here was that Australia would have 6 Senators per state, not 2. In fact, Section 9 of the Australian Constitution says that if the Commonwealth Parliament doesn’t make laws for the uniform election of Senators throughout the country, State Parliaments could make laws for the election of their own Senators.

This distinction meant that the House of Representatives would represent the interests of the Australian public, through their local MPs. Meanwhile, it was intended that Senators would represent the interests of their respective states. This is also true for the referendum system.

It’s also why the Governor-General issues the writs, literally written legal documents, to hold elections for the House of Representatives throughout Australia. Meanwhile, Governors would issue the writs for Senate elections in their respective states. So, in theory, Senators don’t answer to political parties; they were meant to answer to the state they were elected to represent.

On the face of it, this would suggest that Lidia Thorpe owns her seat. But the Australian Constitution has changed since 1901. Section 15 of the Constitution, is concerned with replacing ‘casual vacancies,’ meaning Senators who die, or are otherwise unable to hold office, during their term, stated that the relevant State Parliament would appoint a successor, or if not in session, the Governor, on the advice of their Cabinet, would appoint a temporary successor.

A seat will be considered vacant if the holder dies, resigns, is unable to fulfill their duties due to being incapacitated by health problems or is otherwise absent from Parliament for two consecutive months, or becomes unfit for office by breach of the Constitution.

By 1946, a constitutional convention developed that the former Senator’s party would nominate candidates to fill the position. Unfortunately, constitutional conventions aren’t binding. In the lead-up to the Whitlam Dismissal, two Senators vacated their seats. Labor Senator Lionel Murphy was appointed to the High Court of Australia, meaning he couldn’t hold office. But New South Wales Premier Tom Lewis, from the Liberal Party, didn’t think Murphy’s vacation was covered by the convention; he only believed it applied to death or incapacitation by health problems. So the two Houses of Parliament, controlled by the government, appointed the independent Cleaver Burton in a joint session.

The death of Bertie Milliner, a Labor Senator from Queensland created the second vacancy. While the Queensland Liberal-Country government of Premier Joh Bjelke-Petersen, which controlled Queensland’s unicameral Parliament, appointed Labor Party member Albert Field, he was not the candidate nominated by the Queensland Labor Party. Labor would take this dispute to the High Court, costing Labor their control of the Senate when the Liberal Party wouldn’t follow convention and have one of their Senators unable to vote, a practice called ‘pairing.’

Section 15 would be completely rewritten by a constitutional amendment in 1977, in light of this failure of the convention. It recognised that the seat is, first and foremost, controlled by the person holding the seat. If a sitting Senator leaves the party they were elected as a member of, the seat remains under their control. In theory, a Senator could change their party allegiance, or become an independent, as many times as they wanted within their term in Parliament.

The focus on the Senator being chosen by the people, rather than the seat being given won by the party and then being filled by that party’s preferred candidate, can be seen in the second paragraph, which refers to the “Senator chosen by the people of a State,” who is merely endorsed by, and “publicly represented” as a member of, a particular party.

There are only two exceptions to this rule, where the seat will revert back to the control of the party. If a Senator leaves a party, and subsequently vacates their seat during the same term, their replacement will belong to the original party. This is a constitutional recognition of the original convention.

The other exception, which is not relevant here, is that if the Senator-elect leaves their party before taking office, the seat will be deemed vacant, and the original party again fills that seat.

One other matter being brought up is whether Thorpe actually has genuine personal support, which would presumably be indicated via below-the-line votes - where you actually vote for a person, not just a party ticket.

At the 2022 election, she received 40,174 below-the-line votes with 484,561 voting above-the-line. All other Greens candidates on the same ticket received between 1,000-2,000 individual votes each.

Compare that to Labor and the Liberals, where their candidate who was first on the ticket (Linda White and Sarah Henderson respectively) received no more than 31,000 votes each.

Thorpe's below-the-line vote was less than Janet Rice's in 2019 - when she had 46,205 votes - but the overall party vote rise by more than 100,000.

In accordance with Section 15 of the Australian Constitution, Lidia Thorpe will own her Senate seat until that seat is up for election in 2028. The Greens will only get control of the seat back if Senator Thorpe vacates it, or in the unlikely situation there is a double dissolution in 2025 and she loses her seat at that election.

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Elijah Granet’s ‘Better AustLII’ web extension.


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