The Constitution, Federation and Structures of Government

The Nature and Purpose of the Commonwealth of Australia Constitution Act 1901

The Commonwealth of Australia Constitution Act 1901 (UK) is the supreme law of Australia. It is an Act of the British Parliament that established the Commonwealth of Australia by federating six self-governing colonies — New South Wales, Victoria, Queensland, South Australia, Western Australia, and Tasmania — into a single nation on 1 January 1901. The Constitution operates as a foundational legal document that both creates the institutions of government and constrains the exercise of their powers.

The Constitution serves several distinct purposes:

• Constitutive function: It creates the three branches of the Commonwealth government — the legislature (Parliament, Chapter I), the executive (Chapter II), and the judiciary (Chapter III). Without the Constitution, these institutions would have no legal existence.
• Distributive function: It distributes legislative power between the Commonwealth and the states, allocating specific subject matters to the Commonwealth Parliament under section 51 (concurrent powers) and section 52 (exclusive powers), while residual powers remain with the states.
• Protective function: It contains a small number of express rights, including the right to trial by jury for serious Commonwealth offences (s 80), freedom of religion (s 116), and the right to just terms for compulsory acquisition of property (s 51(xxxi)).
• Limiting function: It imposes structural constraints — such as the requirement that money bills originate in the House of Representatives (s 53) — that prevent any single branch from accumulating unchecked power.

A critical feature is the doctrine of constitutional supremacy: where a law is inconsistent with the Constitution, it is invalid to the extent of the inconsistency (Australian Communist Party v Commonwealth (1951) 83 CLR 1). This is enforced by the High Court of Australia, which acts as the constitutional guardian under Chapter III.

Worked Example: In Commonwealth v Tasmania (1983) 158 CLR 1 (the Tasmanian Dam Case), the High Court upheld Commonwealth legislation blocking a dam on the Franklin River. The Commonwealth relied on the external affairs power (s 51(xxix)) in conjunction with Australia's obligations under the World Heritage Convention. The case illustrates how the Constitution's grant of legislative power, when interpreted expansively by the High Court, can allow the Commonwealth to intervene in matters traditionally considered state affairs — demonstrating both the distributive and limiting functions of the Constitution simultaneously.

The Federal Structure: Commonwealth, State/Territory and Local Government

Australia operates under a federal system of government, meaning that sovereign power is divided between a national government and regional governments by a supreme legal instrument — the Constitution. This stands in contrast to a unitary system (where power flows from the centre) and a confederal system (where the central government is weak relative to the regions).

The Australian federal structure comprises three tiers:

• Tier 1 — Commonwealth (Federal) Government: Established by the Constitution, the Commonwealth Parliament has legislative power over specific subject matters listed in the Constitution. Section 51 sets out 39 concurrent heads of power (including taxation, trade and commerce, and corporations), while section 52 lists exclusive powers (such as defence and customs). Under section 109, where a valid Commonwealth law is inconsistent with a state law, the Commonwealth law prevails and the state law is invalid to the extent of that inconsistency. The Commonwealth government has three branches: Parliament (bicameral — Senate and House of Representatives), the Executive (formally the Governor-General-in-Council; practically the Prime Minister and Cabinet), and the Judiciary (High Court and federal courts).
• Tier 2 — State and Territory Governments: Australia has six states and two self-governing territories (Australian Capital Territory and Northern Territory). Each state has its own constitution, parliament, executive and court system. States possess plenary legislative power — that is, unlimited power to make laws for the peace, order and good government of the state, subject to the Commonwealth Constitution. Territories derive their power from Commonwealth legislation (the Australian Capital Territory (Self-Government) Act 1988 and Northern Territory (Self-Government) Act 1978), making their status constitutionally weaker than states. Queensland is notable for having a unicameral Parliament — the Legislative Assembly — after the abolition of the Legislative Council in 1922.
• Tier 3 — Local Government: Local councils are not mentioned in the Constitution and have no independent constitutional status. They are creatures of state legislation (in Queensland, the Local Government Act 2009 and City of Brisbane Act 2010). They exercise delegated powers to regulate matters of local concern — land use, waste, local roads, and community facilities. A 1988 referendum to recognise local government in the Constitution failed, confirming their subordinate position.

Section 109 in practice: In Momcilovic v The Queen (2011) 245 CLR 1, the Court considered inconsistency issues arising from the interaction of state and Commonwealth law. The principle is that the Commonwealth's paramountcy under s 109 means states must always legislate with awareness of whether valid Commonwealth law already covers the field.