Many Acts of Parliament delegate to the executive government the power to make detailed rules and regulations (legislative instruments). Instruments made in this way are subject to the power of either House to veto or disallow them.
In most cases, within 15 sitting days after tabling a senator may give notice of a motion to disallow the legislative instrument. If the motion is agreed to, the instrument is disallowed and ceases to have effect. If a notice of motion to disallow a legislative instrument has not been resolved or withdrawn within 15 sitting days after having been given, the instrument is deemed to have been disallowed and automatically ceases to have effect.
Brief Guide to Senate Procedure No. 19 – Disallowance
Senate Brief No. 8 – The Senate and legislation