Origins and role
The Australian Senate in 1923
The Commonwealth of Australia Constitution Act (Imp.) of 1900 established the Senate as part of the new system of dominion government in newly federated Australia. From a comparative governmental perspective, the Australian Senate exhibits distinctive characteristics. Unlike upper Houses in other Westminster system governments, the Senate is not a vestigial body with limited legislative power. Rather it was intended to play – and does play – an active role in legislation. Rather than being modeled solely after the House of Lords, as the Senate of Canada was, the Australian Senate was in part modeled after the United States Senate, by giving equal representation to each state and equal powers with the lower house. The Constitution intended to give less populous states added voice in a Federal legislature, while also providing for the revising role of an upper house in the Westminster system.
Although the Prime Minister of Australia and Treasurer of Australia, by convention, are members of the House of Representatives (after John Gorton was appointed prime minister in 1968, he resigned from the Senate and was elected to the House), other members of the Cabinet of Australia may come from either house, and the two Houses have almost equal legislative power. As with most upper chambers in bicameral parliaments, the Senate cannot introduce or amend appropriation bills (bills that authorise government expenditure of public revenue) or bills that impose taxation, that role being reserved for the lower house; it can only approve, reject or defer them. That degree of equality between the Senate and House of Representatives reflects the desire of the Constitution's authors to address smaller states' desire for strong powers for the Senate as a way of ensuring that the interests of more populous states as represented in the House of Representatives did not totally dominate the government. This situation was also partly due to the age of the Australian constitution it was enacted before the confrontation in 1909 in Britain between the House of Commons of the United Kingdom and the House of Lords, which ultimately resulted in the restrictions placed on the powers of the House of Lords by the Parliament Acts 1911 and 1949.
In practice, however, most legislation (except for private member's bills) in the Australian Parliament is initiated by the Government, which has control over the lower house. It is then passed to the Senate, which has the opportunity to amend the bill, pass or reject it. In the majority of cases, voting takes place along party lines, although there are occasional conscience votes.