On 27 February Labor Senator Mark Arbib announced his intention to resign from the Ministry and the Senate. His resignation from the Ministry took effect from 2 March, and he resigned from the Senate on 5 March.
This FlagPost lists recent casual vacancies and describes the steps for filling them.
The most recent Senate casual vacancy followed the resignation of Senator Helen Coonan on 22 August 2011. At a joint sitting of the two Houses of the Legislature of New South Wales held on 13 October 2011 in accordance with the provisions of section 15 of the Commonwealth of Australia Constitution Act, Arthur Sinodinos was chosen as the replacement.
Since 1901 there have been 134 occasions when a replacement senator has been chosen or appointed to fill a casual vacancy; these are listed in the Parliamentary Handbook.
Twenty-one of the currently serving senators commenced their terms as a result of a casual vacancy. They are Senators Carr, Abetz, Lundy, Conroy, Heffernan, Payne, Crossin, Brandis, Humphries, Fifield, Fierravanti-Wells, Carol Brown, Bernardi, Boyce, Birmingham, Fisher, Cormann, Bushby, Collins, Back, and Sinodinos.
As stated in Senate Brief No. 1, Electing Australia’s Senators:
Section 15 of the Constitution, as it was amended in 1977, provides that when a casual vacancy occurs in the Senate, through resignation or death of a senator, a new appointment is made by the Parliament of the state which that senator represented, or, in the cases of the territories, by their legislative assemblies. The 1977 amendment, however, provided for the inclusion of a condition, which had prior to that date been a convention only, that the vacant place should always be filled by a member of the same political party or group as the vacating senator. The new senator then holds the position for the remainder of the term of the senator replaced. This provision is designed to preserve between elections the proportional representation of political parties as determined by the electors.
When a vacancy occurs the President of the Senate writes to the State Governor, advising that a vacancy has occurred. The procedure followed in New South Wales is that the Governor then writes to the presiding officers of both chambers advising them of the vacancy, and negotiations follow between the chambers regarding the date and time of a joint sitting of both chambers to decide upon the person to fill the vacancy. The joint sitting will take place on Tuesday 6 March 2012. It is usual for the Legislative Assembly Leader of the party in which the vacancy has occurred (in this case the Leader of the Opposition) to nominate the candidate the party has preselected; the Leader of the Opposition in the Legislative Council, in this case, would second the nomination. Should there be more than one nomination an open ballot would take place. At the conclusion of the joint sitting the President notifies the Governor in writing of the name of the person elected, and the Governor in turn notifies the President of the Senate. Other arrangements apply in the case of Queensland and the ACT and Northern Territory.
Further information about the time in which vacancies should be filled and the procedure to be followed should the state houses be in recess can be found in Chapter 4 of Odgers’ Australian Senate Practice, 12th edition.