Senate (Quorum) Act 1991 No. 138 of 1991 An Act to determine the quorum of the Senate Contents 1 Short title 2 Commencement 3 Quorum Senate (Quorum) Act 1991 No. 138 of 1991 An Act to determine the quorum of the Senate [Assented to 27 September 1991] The Parliament of Australia enacts: 1 Short title This Act may be cited as the Senate (Quorum) Act 1991. 2 Commencement This Act commences on the day after the day on which it receives the Royal Assent. 3 Quorum The presence of at least one‑quarter of the whole number of the senators is necessary to constitute a meeting of the Senate for the exercise of its powers.