Under the conventions of the Westminster system, the government of the day and the prime minister must achieve and maintain the confidence of this House in order to gain and remain in power.

The number of members is not fixed but can vary with boundary changes resulting from electoral redistributions, which are required on a regular basis.

The House of Representatives chamber is designed to seat up to 172 members, with provision for an ultimate total of 240 to be accommodated.

Under section 24 of the Constitution, each state is entitled to members based on a population quota determined from the "latest statistics of the Commonwealth".

[7] Until its repeal by the 1967 referendum, section 127 prohibited the inclusion of Aboriginal people in section 24 determinations as including the Indigenous peoples could alter the distribution of seats between the states to the benefit of states with larger Aboriginal populations.

In practice, by convention, the person who can control a majority of votes in the lower house is invited by the governor-general to form the government.

The opposition party's main role in the House is to present arguments against the government's policies and legislation where appropriate and attempt to hold the government accountable as much as possible by asking questions of importance during question time and during debates on legislation.

[citation needed] Australian parliaments are notoriously rowdy, with MPs often trading colourful insults.

[15] This system has remained in place ever since, allowing the Coalition parties to safely contest the same seats.

[18] The main elements of the operation of preferential voting for single-member House of Representatives divisions are as follows:[19][20] Following the full allocation of preferences, it is possible to derive a two-party-preferred figure, where the votes have been allocated between the two main candidates in the election.

Under the Constitution, the governor-general has the power to appoint and dismiss the "Queen's [or King's] Ministers of State" who administer government departments.

Cabinet meetings are strictly private and are frequently held to discuss vital issues and make policy decisions.

[23] In practice, the Federal Executive Council meets solely to endorse and give legal force to decisions already made by the Cabinet.

[22] This provision was included in the Constitution (section 64) to enable the inaugural ministry, led by Edmund Barton, to be appointed on 1 January 1901, even though the first federal elections were not scheduled to be held until 29 and 30 March.

[25] After the 1949 election, Bill Spooner was appointed a minister in the Fourth Menzies ministry on 19 December, however his term as a Senator did not begin until 22 February 1950.

[26] The provision was also used after the disappearance and presumed death of the Liberal prime minister Harold Holt in December 1967.

They provide the opportunity for all MPs to ask questions of ministers and public officials as well as conduct inquiries, examine policy and legislation.

The ability of the chambers of Parliament to establish committees is given in section 49 of the Constitution, which states that, "The powers, privileges, and immunities of the Senate and of the House of Representatives, and of the members and the committees of each House, shall be such as are declared by the Parliament, and until declared shall be those of the Commons House of Parliament of the United Kingdom, and of its members and committees, at the establishment of the Commonwealth.

One of the most significant powers is the ability to summon people to attend hearings in order to give evidence and submit documents.

[31] Other powers include, the ability to meet throughout Australia, to establish subcommittees and to take evidence in both public and private hearings.

Every participant, including committee members and witnesses giving evidence, are protected from being prosecuted under any civil or criminal action for anything they may say during a hearing.

[31][29] Types of committees include:[31] Standing committees, which are established on a permanent basis and are responsible for scrutinising bills and topics referred to them by the chamber; examining the government's budget and activities and for examining departmental annual reports and activities.

The Federation Chamber cannot, however, initiate or make a final decision on any parliamentary business, although it can perform all tasks in between.

[37] The concept of a parallel body to expedite Parliamentary business, based on the Australian Federation Chamber, was mentioned in a 1998 British House of Commons report,[38] which led to the creation of that body's parallel chamber Westminster Hall.