What is parliamentary supremacy?

Parliamentary supremacy is the principle that the Parliament is the supreme law-making body within its constitutional jurisdiction, with the power to pass any legislation within that jurisdiction and to amend, repeal, or override its own previous laws. The principle is inherited from the Westminster system but operates differently in Australia because of the written federal Constitution.

In the United Kingdom, parliamentary supremacy (or parliamentary sovereignty) is essentially unrestricted: the UK Parliament can in theory pass any law on any subject and there is no superior court that can strike down its legislation. In Australia, the federal Parliament's power is limited by the Australian Constitution. The High Court of Australia interprets the Constitution and can strike down federal legislation that exceeds the Commonwealth's enumerated heads of power in section 51 or elsewhere in the Constitution, or that breaches an express or implied constitutional limit.

Within their constitutional jurisdiction, however, Australian parliaments are supreme. The federal Parliament can pass any law within its constitutional powers. State parliaments can pass any law within their general legislative power, subject to specific federal overrides (such as the inconsistency rule in section 109 of the Constitution, which gives federal laws priority over inconsistent state laws). Parliaments can amend or repeal their own previous laws.

The principle has practical implications. Parliament does not have to follow its own previous decisions, and a court ruling on the interpretation of legislation can be overridden by Parliament passing a clarifying or overriding amendment. Several recent Australian examples include Parliament's overriding of High Court decisions on specific aspects of tax law, immigration powers, and discrimination law. The principle also means that Parliament can change constitutional conventions over time, with practices that were once mandatory becoming discretionary or vice versa. The interaction between parliamentary supremacy and the implied constitutional rights recognised by the High Court (such as the implied freedom of political communication) remains a central field of Australian constitutional scholarship.