Gary John Joseph Humphries is a Deputy President of the Administrative Appeals Tribunal. He was a member of the Australian Senate representing the Australian Capital Territory for the Liberal Party of Australia from 2003 to 2013. He was the Chief Minister of the Australian Capital Territory from 2000 to 2001; and was elected to the first parliament of the Australian Capital Territory, in 1989, later representing the Molonglo electorate until 2003.

The Senate is the upper house of the bicameral Parliament of Australia, the lower house being the House of Representatives. The composition and powers of the Senate are established in Chapter I of the Constitution of Australia. There are a total of 76 senators: 12 are elected from each of the six Australian states regardless of population and 2 from each of the two self-governing internal Australian territories. Senators are popularly elected under the single transferable vote system of proportional representation.