The committees of the Australian Senate are committees of Senators, established by the Australian Senate, for purposes determined by that body. Senate committees are part of the operation of the Australian parliament, and have for some decades been involved in maintenance of government accountability to the Australian parliament, particularly through hearings to scrutinise the budget, and through public inquiries on policy questions.

The existence of parliamentary committees is mentioned in section 49 of the Constitution of Australia, which makes reference to 'The powers, privileges, and immunities of the Senate and of the House of Representatives, and of the members and the committees of each House...' However, the Senate had few committees, engaged in limited activities, until 1970.^[1] A number of domestic committees had operated since the establishment of the parliament, but prior to 1970 the only significant committee to be established was the Regulations and Ordinances Committee in 1932, one of the legislative scrutiny committees (see below).

In 1970, the present committee system was created, with a series of standing (permanent) committees established that mirrored the portfolio activities of government.^[1] These reforms significantly enhanced the expertise and power of the Senate:

The Senate is now undergoing the most fundamental and dramatic changes witnessed in the Commonwealth Parliament since the States decided to federate 70 years ago. The introduction of a wide-ranging committee system will make the red-carpeted Upper House potentially the most powerful parliamentary chamber in Australia.^[2]

These reforms were also significant in that they gave to Senate committees the role of examining the budget (what is referred to as the estimates process or estimates hearings), which had hitherto been confined to the Senate and its committee of the whole. The role of the committees was enhanced by three subsequent developments. First, in 1982 the Scrutiny of Bills Committee was established, which, in examining all bills, played a role that complemented that of the examination of all delegated legislation by the Regulations and Ordinances Committee. Second, in 1989 the Senate adopted procedures for the systematic referral of bills to committees, increasing the level of legislative scrutiny taking place within parliament.^[3] Third, in 1993, the committees adopted a more extensive procedure for consideration of the budget, creating a second opportunity each year for Senators to follow up issues identified during the initial budget estimates hearings. These second hearings are referred to as supplementary budget estimates. Though the committee system was restructured in 1994, 2006 and again in 2009, the range of functions has remained essentially the same.

The functions of committees depend on the type of committee and on the work it is undertaking. Most of the committees are established under the Senate's Standing Orders.

These are the committees of the 47th Parliament that exist within each category:^[16]

The Senate's committees are formed at the commencement of each new parliament, in accordance with rules set out in the Standing Orders. The committees exist until the first day of the following parliament, in contrast to the lower house committees, which cease to exist as soon as parliament is prorogued for an election.

The most important and high profile of the committees are the pairs of standing committees. These each have six members. The chairman of each legislation committee is chosen from amongst the government members, the deputy chair from amongst non-government members. The reverse is the case for the references committees. Because the chair has a casting vote in the event of a committee vote being tied, the government effectively controls the legislation committees, while the non-government parties control the references committees.^[17]

The membership and rules of committees, including those that operated during the Coalition's period of control, are shown below:^[18]

Committees have two types of members: full members and participating members. In the case of standing committees, full members are the six outlined above. In addition, however, any Senator may arrange for the Senate to agree to their being made a participating member of the committee. This gives them the same rights as full members, with the important exception of being unable to vote on motions in private meetings of the committees.

The committees are governed by the Standing Orders of the Senate, as well as being able to pass their own resolutions to govern certain aspects of their operations (such as the processing of correspondence and submissions to inquiries).

Committees are designed to assist the Senate as a whole. Thus the main formal structure of their work is that the Senate refers something to a committee for examination, and the committee reports back to the Senate on that matter. These reports are tabled during parliamentary sittings, but can also be presented when the Senate is not in session.^[19] Committees can gather evidence and will often hold public hearings to assist this process.^[20] To gather their evidence committees can (with exceptions) travel from place to place to hear evidence.^[21] Committees are able to order the production of documents and the appearance of witnesses (powers that are in practice used very sparingly).^[22][23] Most evidence taken by committees (both written submissions and transcripts of public hearings) is published, however committees have the power to take evidence confidentially (in camera), and regularly do so.^[24] Committees hold both public hearings and conduct business at private meetings. The minutes of private meetings are confidential (in contrast, for example, to those of New South Wales parliamentary committees).^[25]

The rules governing committees are slightly different when conducting budget estimates hearings.^[26] In particular, during estimates hearings,

• any Senator may ask questions of the officials appearing before the committee (normally only members can ask questions)
• no evidence can be taken on a confidential basis (normally this is an option available to a committee)
• under Standing Orders, Senators may direct questions to any government agency, but only within the portfolio areas for which the committee has oversight. The committee cannot restrict the agencies to which Senators may direct questions (although the committee can control whether this happens at the public hearing, or whether it must be done in writing afterwards).

A typical year in the life of a Senate legislation committee will see it conduct eight days of hearings around budget estimates, in three sessions: February (additional estimates), May/June (the main budget estimates) and October/November (supplementary budget estimates). In addition, it will typically conduct several inquiries into pieces of legislation being considered by the parliament. A references committee will conduct inquiries into policy issues referred to it by the Senate. Each of these inquiries will usually result in a report tabled in the Senate (there may be exceptions if an election intervenes during the committee's deliberations). A consolidated list of the reports^{[dead link]} prepared by all Senate committees since 1970 is published by the Department of the Senate.

The impact of the Senate's committees varies and has been the subject of debate. The work of the committees is frequently more consensual and less partisan than activity in the parliamentary chambers, and unanimous committee reports that agree recommendations across party lines are not uncommon.^[33] As a result, these recommendations may contribute to subsequent government policy announcements and occasionally to changes in government actions. The work of the regulations and ordinances committee has led to revisions of subordinate legislation in significant respects.^[34] Committee scrutiny of bills has contributed to them being amended^[35] or withdrawn.^[36] The impact of committees on legislation overall has however been described as 'rather limited',^[37] particularly as the committees that review bills are controlled by a government majority.

Senate committees can be affected by the party composition of the Senate. The Clerk of the Senate, Harry Evans, argued that a government majority of seats in the Senate resulted in limitations on what the committees inquired into, and how readily governments responded to their queries and requests for information.^[38] Statistics published by centrist political party the Australian Democrats have been used to support the contention that committee operations have been inhibited by government control of the Senate, particularly in respect of selection of topics for committee inquiry.^[39] However Senator Minchin, the leader of the government in the Senate in the mid-2000s, pointed out that their political rivals had previously cut off debate on more bills in the Senate than had his government.^[40]

• Australian House of Representatives committees