List of Western Australian state by-elections

The list of Western Australia state by-elections includes every by-election held in the Australian state of Western Australia. By-elections occur whenever there is a vacancy in the Legislative Assembly (or, historically, the Legislative Council), although an imminent state election may allow the vacancy to remain until the dissolution of parliament.

Section 67 of the Electoral Act 1907 requires the Speaker to issue a writ for a by-election to fill the vacancy. This can either take place after a resolution of the House if Parliament is in session, or simply upon the cause being established by the Speaker acting alone if the Parliament is in adjournment for more than 7 days.

A by-election occurs whenever there is a vacancy in the Legislative Assembly. Vacancies can occur for the following reasons, according to Section 38 of the Constitution Acts Amendment Act 1899.

The member:

Additional reasons not within Section 38 include:

Until a constitutional amendment in 1947, it was necessary for members who were appointed as a Minister to resign their seat and contest their seat at a ministerial by-election. This was because the Ministers became members of the Executive Council, which reported to the Governor of Western Australia and was therefore deemed an "office of profit" under the Crown. Most ministerial by-elections were a formality with the Minister being re-elected unopposed, but on two occasions, in 1901 and 1917, Ministers were defeated at the by-elections, in the former case directly causing the fall of the Morgans Ministry.

† Won by acclamation; this date is the date of the return of the writ.

...
Wikipedia