Limitations on Commonwealth Power and Intergovernmental Immunities

Introduction

The Australian Constitution imposes both express and implied limitations on the legislative and executive powers of the Commonwealth. These limitations protect the States as distinct political entities within the federal system, safeguard individual rights, and maintain the constitutional structure of government. The most significant implied limitation is the Melbourne Corporation principle, which prohibits the Commonwealth from enacting laws that discriminate against the States or that would undermine their capacity to function as independent governments. The express limitations include prohibitions on discrimination in trade and commerce (s 99), religious establishment (s 116), and discrimination on the basis of State residence (s 117), among others.

The Implied Freedom of Political Communication

The High Court has recognised an implied freedom of political communication as an essential incident of the system of representative government established by the Constitution. First articulated in Australian Capital Television Pty Ltd v Commonwealth (1992) 177 CLR 106 and Nationwide News Pty Ltd v Wills (1992) 177 CLR 1, this freedom is implied from ss 7 and 24 of the Constitution, which require that members of the Senate and House of Representatives be “directly chosen by the people.” The implication is that the people must be able to communicate freely on political matters to make an informed choice. The implied freedom is not a personal right but a limitation on legislative power: it invalidates laws that impose an impermissible burden on political communication. The test, as reformulated in McCloy v New South Wales (2015) 257 CLR 178, involves a structured proportionality analysis: the law must pursue a legitimate purpose, be suitable and necessary to achieve that purpose, and be adequate in its balance.

The Melbourne Corporation Principle

In Melbourne Corporation v Commonwealth (1947) 74 CLR 31, the High Court held that the Constitution impliedly limits Commonwealth legislative power to protect the States’ capacity to function as independent entities within the federal system. The case concerned the Banking Act 1945 (Cth), which prohibited private banks from conducting banking business for State governments. The Court held that while the Commonwealth had power over banking under s 51(xiii), the law was invalid because it discriminated against the States and impaired their capacity to function. The Melbourne Corporation principle has two limbs: (1) the Commonwealth may not discriminate against the States or their instrumentalities, and (2) the Commonwealth may not enact laws that curtail or restrict the States’ capacity to function as independent governments.

The principle was reaffirmed and refined in Queensland Electricity Commission v Commonwealth (1985) 159 CLR 192. The case concerned a Commonwealth law that established a special industrial tribunal for the Queensland electricity industry, overriding the State’s own industrial relations system. The High Court held the law invalid because it was discriminatory — it singled out the Queensland electricity industry for special treatment — and because it curtailed Queensland’s capacity to function as an independent government by impairing its control over its own industrial relations.

In Austin v Commonwealth (2003) 215 CLR 185, the High Court applied the Melbourne Corporation principle to invalidate provisions of the Superannuation Contributions Tax (Members of Constitutionally Protected Superannuation Funds) Assessment and Collection Act 1997 (Cth), which imposed a surcharge on the superannuation contributions of State judges. The Court held that the law impermissibly burdened the States’ ability to provide for the remuneration of their own judges, thereby impairing the independence of the State judiciaries and the capacity of the States to function as independent politics.

The Engineers’ Case and the Rejection of Implied Immunity

Before 1920, the High Court had recognised an implied immunity of instrumentalities — derived from American constitutional doctrine — which held that neither the Commonwealth nor the States could interfere with the governmental functions of the other. In D’Emden v Pedder (1904) 1 CLR 91, the Court applied this doctrine to invalidate a Tasmanian stamp duty on receipts issued to Commonwealth officers. In The Federated Amalgamated Government Railway and Tramway Service Association v The New South Wales Railway Traffic Employees Association (1904) 1 CLR 678 (the Railway Servants Case), the Court held that State railway employees were bound by State but not Commonwealth industrial law.

The Engineers’ Case (Amalgamated Society of Engineers v Adelaide Steamship Co Ltd (1920) 28 CLR 129) overruled these earlier authorities. In a landmark judgment delivered by Sir Isaac Isaacs, the High Court rejected the implied immunity of instrumentalities as a matter of constitutional interpretation. The Court held that the Constitution should be interpreted according to its ordinary and natural meaning, without importing implications derived from American federalism. The effect of the Engineers’ Case was to expand Commonwealth power by holding that Commonwealth laws enacted under s 51 applied to State governments and their instrumentalities, unless the Constitution expressly provided otherwise. The Engineers’ Case is widely regarded as the most important decision in Australian constitutional law, fundamentally reshaping the federal balance.

Express Limitations on Commonwealth Power

The Constitution contains several express limitations on Commonwealth power:

Section 99 prohibits the Commonwealth from giving “preference” to one State or part of a State over another in any law or regulation of trade, commerce, or revenue. This provision prevents the Commonwealth from favouring particular States in its trade and commerce legislation, but it does not prohibit discrimination between States generally.

Section 100 guarantees the “free use of the State’s rivers” for irrigation and conservation purposes, but is subject to the Commonwealth’s legislative power. The provision has been narrowly construed.

Section 114 prohibits the Commonwealth from imposing any tax on State property, and prohibits the States from imposing any tax on Commonwealth property. This provision protects the respective governments from fiscal burdens imposed by the other level of government.

Section 116 provides that the Commonwealth shall not make any law for establishing any religion, imposing any religious observance, or prohibiting the free exercise of any religion, and that no religious test shall be required as a qualification for any Commonwealth office. This provision has been interpreted restrictively by the High Court.

Section 117 prohibits discrimination on the basis of State residence: a resident of one State may not be subjected to any “disability or discrimination” in another State that would not apply if they were a resident of that other State.

Tied Grants Under Section 96

Section 96 empowers the Commonwealth to grant financial assistance to any State “on such terms and conditions as the Parliament thinks fit.” This provision has enabled the Commonwealth to exercise significant influence over State policy areas, such as education, health, and infrastructure, by attaching conditions to grants. The High Court has consistently upheld the validity of tied grants, even where the conditions relate to matters within State legislative competence. In Victoria v Commonwealth (1926) 38 CLR 399 (the Federal Aid Roads Case), the Court held that s 96 confers a broad and unqualified power. The practical effect of s 96 has been to centralise financial power in the Commonwealth and to enable Commonwealth involvement in areas of traditional State responsibility.

Inconsistency of Laws Under Section 109

Section 109 provides that when a State law is inconsistent with a Commonwealth law, the Commonwealth law prevails and the State law is invalid “to the extent of the inconsistency.” The High Court has identified three categories of inconsistency: (1) direct inconsistency, where it is impossible to obey both laws simultaneously; (2) indirect inconsistency, where the Commonwealth law evinces an intention to “cover the field” on a particular subject, thereby excluding State law; and (3) where the Commonwealth law confers a right or privilege that the State law purports to deny. The test for whether the Commonwealth has “covered the field” is one of legislative intention, to be discerned from the terms and subject matter of the Commonwealth law.