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Odgers' Australian Senate Practice Thirteenth Edition

Chapter 4 - Elections for the Senate

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Method of filling casual vacancies

Casual vacancies are filled in accordance with section 15 of the Constitution.

The purpose of the current section 15, inserted by an amendment of the Constitution in 1977, is to preserve as much as possible the proportional representation determined by the electors in elections for the Senate.

The main features of the section are as follows:

When a casual vacancy arises, the Houses of the Parliament, or the House where there is only one House, of the state represented by the vacating senator chooses a person to hold the place until the expiration of the term.

If the Parliament is not in session, the Governor of the state, with the advice of the Executive Council thereof, may appoint a person to hold the place until the expiration of 14 days from the beginning of the next session of the parliament of the state or the expiration of the term, whichever first happens.

A person chosen is to be, where relevant and possible, a member of the party to which the senator whose death or resignation gave rise to the vacancy. The pertinent paragraph of section 15 states:

Where a vacancy has at any time occurred in the place of a senator chosen by the people of a State and, at the time when he was so chosen, he was publicly recognised by a particular political party as being an endorsed candidate of that party and publicly represented himself to be such a candidate, a person chosen or appointed under this section in consequence of that vacancy, or in consequence of that vacancy and a subsequent vacancy or vacancies, shall, unless there is no member of that party available to be chosen or appointed, be a member of that party.

Section 15 also provides:

Where —

  1. (a) in accordance with the last preceding paragraph, a member of a particular political party is chosen or appointed to hold the place of a senator whose place had become vacant; and
  2. (b) before taking his seat he ceases to be a member of that party (otherwise than by reason of the party having ceased to exist),

he shall be deemed not to have been so chosen or appointed and the vacancy shall be again notified in accordance with section twenty-one of this Constitution.

Casual vacancies arising in the Senate representation of the Australian Capital Territory or the Northern Territory are filled by the respective territory legislative assemblies. If the legislature is out of session, a temporary appointment can be made in the case of the Australian Capital Territory by the Chief Minister, and in the case of the Northern Territory by the Administrator. Provisions relating to political parties, similar to those of section 15 of the Constitution, also apply.[46]

The term of a senator filling a casual vacancy commences on the date of his or her choice by the appointing body. When a senator is appointed to a vacant place by the governor of a state and the appointment is "confirmed" by the state parliament within the 14 days allowed by section 15, the senator is not regarded as commencing a new term on the appointment by the parliament and is not sworn again.[47] The 14 day period is regarded as commencing on the day after the first day of the session, in accordance with the normal rule of statutory interpretation. If there is a "gap" between the expiration of the 14 day period and the appointment of the senator by the parliament, the senator is sworn again.[48]


46. Commonwealth Electoral Act, s. 44.
47. Ruling of President Baker, upheld by Senate, 3/9/1903, J.157; 4/9/1903, J.162.
48. Case of Senator Vardon, 5/8/1921, J.330; 9/8/1921, J.332.