In Australian politics, a casual vacancy is caused when a member of either house (the Senate or the House of Representatives):
- dies
- resigns mid-term The term “resign” is not to be confused with “retire”. A resignation is a voluntary decision by a parliamentarian to end their term early, at a time of their own choosing. A retirement is an involuntary act whereby the sitting member chooses to see out their current term but not to contest the next general election, whenever it is held. The choice of the date of that election is not within the control of the member, but of the government., or
- is expelled from Parliament and their seat declared vacant. There has only ever been one such case, that of Hugh Mahon, who was expelled from the House of Representatives in 1920.
Casual vacancies are handled in different manners depending on the house concerned.
Senate
Casual Senate vacancies in the representation of the States
Section 15 of the Australian Constitution requires the parliament of the state that the senator represented to choose a replacement. In the event that the state parliament is not in session, the Governor of the state (acting on the advice of the relevant Premier) may choose the replacement.
Prior to 1977 it was an established convention, but not a constitutional requirement, that the state parliament choose a replacement from the same political party as their predecessor. It had also been the practice for the relevant party to provide a list of suitable names to the state premier, and for the state parliament to make the choice. In 1975, both these conventions were breached, and in the former case, twice.
In early February 1975, Lionel Murphy (Australian Labor Party, New South Wales) resigned from the Senate to take up an appointment as a judge of the High Court. On 27 February, the NSW Liberal Premier Tom Lewis appointed Cleaver Bunton, a former long-serving Mayor of Albury, who was not affiliated with any political party. Bunton sat as an independent senator.
On 30 June 1975, the Queensland Labor Senator Bertie Milliner died suddenly. The Labor Party gave only one replacement name to the Country Party Queensland Premier Joh Bjelke-Petersen - that of Mal Colston. However, on 3 September, on Bjelke-Petersen’s instigation, the Parliament of Queensland appointed Albert Field to the vacancy. Although he had been a member of the Labor Party for 30 years, Field was now only nominally a member of the party and was openly critical of the Labor government of Gough Whitlam. He was expelled from the party as a result of accepting the appointment. Field took his seat in the Senate, but the Labor Party challenged his appointment in the High Court due to doubts as to his eligibility, and he was on leave from the Senate from 1 October for the remainder of his short-lived term “The Field Affair”.
In 1977, the Constitution was changed by referendum to require future Senate casual vacancies to be filled by a member of the same party as the senator vacating the seat.
Casual Senate vacancies in the representation of the Territories
Currently, when a Senate seat representing the Australian Capital Territory (ACT) or the Northern Territory (NT) becomes vacant, the replacement senator is chosen by the relevant territory legislature, under s.44 of the Commonwealth Electoral Act 1918 [1]. This occurred for the first time on 18 February 2003, when Gary Humphries was chosen by the ACT Legislative Assembly to replace Margaret Reid, who had resigned from the Senate on 14 February p. 8815.
Previously, territory casual Senate vacancies were handled in a different way and were the subject of a different law: s.9 of the Senate (Representation of Territories) Act 1973, as amended by the Senate (Representation of Territories) Amendment Act 1980. Under this provision, the replacement senator was elected by a joint sitting of both houses of the Federal Parliament. This only ever occurred twice:
- when Margaret Reid was elected on 5 May 1981 to replace the deceased ACT Senator John Knight [2]
- when Bob McMullan was elected on 16 February 1988 to replace former ACT Senator Susan Ryan, who had resigned. Rules for Joint Sittings: footnote, p.3, [3]
This provision would still be used to fill a casual vacancy in the representation of any external territory (in the event that such a territory ever gains representation).
House of Representatives
Casual vacancies in the House of Representatives are filled by by-election. The government chooses the date of the by-election, and advises the Speaker to issue the appropriate writ.
When a general election is expected within a relatively short time, it has often been the practice not to hold a by-election. This has been justified on the grounds that: (a) the electors of the seat in question should not be burdened with voting twice within a short period of time, when their views are hardly likely to change significantly in that time; and (b) the cost of holding a by-election is high, and it is ultimately the taxpayers who bear this.
Notes