Section 51 of the Constitution of Australia
Section 51 of the Constitution of Australia enumerates the legislative powers granted to Federal Parliament by the Australian States at Federation. The list contains 39 subsections, each referred to as a 'head of power' under which the parliament is empowered to make laws. The section is an exhaustive list, and the federal parliament is not authorized to enact legislation outside of those topics. Australian States may still enact legislation upon the topics in section 51; but Federal law prevails to the extent of any conflict of laws. Powers of the Parliament. The most  important heads of section in terms of supporting contemporary Commonwealth legislation are: Federation was intended to address problems caused by having the separate colonies on the one continent. Section 51 therefore encompasses a group of 'nationhood' powers which reflect what powers a 'nation' was viewed as possessing. These include: The Constitution also grants powers over: Flexibility is allowed by: Judicial interpretation. The High Court of Australia has the jurisdiction to interpret the constitution, an often controversial ability. Many of the court's interpretations have focused on section 51, from cases arising out of disputes between the states and the Commonwealth  Parliament. It was noted in "Pape v Commissioner of Taxation" that taxation power under s51(ii) is not "unlimited" and must be employed so as not to discriminate between States or parts of States. Core and incidental parts of s51 powers. All heads of power in section 51 have an implied incidental area. The incidental area arises when the law operates on persons, Acts, or things outside the actual subject matter of the head of power. Valid laws in the incidental area will have an indirect, but sufficient connection to the head of power. Different judicial tests have arisen to test  if the connection is sufficient. The dominant test is if the law in question is a reasonable and appropriate means of furthering an object or purpose in the power. Other tests are the 'reasonably necessary' test or 'reasonable fulfilment of the purpose'. Justice Mason preferred a 'proportionality' test that took into account the adverse effects of incidental laws. Tied grants. Section 51 appears to limit the areas of federal involvement. However, under section 96 of the Australian Constitution the Commonwealth Parliament has the power to grant money to any State, "on such terms and conditions as the Parliament thinks fit ." In effect, the Commonwealth can make grants subject to States implementing particular policies in their fields of legislative responsibility. Such grants, known as tied grants (since they are tied to a particular purpose), have been used to give the federal parliament influence over state policy matters such as public hospitals and schools. Section 96 does not compel a state to accept a grant, so constitutionally a state may refuse a grant and not implement any policy conditions. However, since a uniform federal system of income tax was introduced in 1942 (under s51(ii)) a vertical fiscal imbalance has arisen and the  Commonwealth Parliament has had a vastly larger budget. It also has control over state borrowings (under subsection iv). This has meant that the Parliament's powers have effectively been extended beyond the constraints of section 51 and other explicit grants of legislative power (e.g. section 52 and section 90).