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Why is Section 109 of the Australian Constitution Important?

Section 109 of the Australian Constitution is a critical section that deals with inconsistencies between federal and state laws. It provides that where there is an inconsistency between a federal law and a state law, the federal law will prevail. This section establishes the supremacy of federal laws and is fundamental to Australia’s federal system of government.

What Does Section 109 Say?

The full text of Section 109 states:

When a law of a State is inconsistent with a law of the Commonwealth, the latter shall prevail, and the former shall, to the extent of the inconsistency, be invalid.

In essence, this section provides that if there is a conflict between a valid federal law and a state law, the federal law will override the state law to the extent of the inconsistency. The state law remains valid except for the part that is inconsistent with the federal law.

Why is Section 109 Important?

There are several reasons why Section 109 is a crucial section of the Constitution:

  • It upholds the supremacy of federal laws and establishes a central principle of Australia’s federal system of government.
  • It prevents the states from enacting laws that conflict or undermine federal laws, promoting national consistency.
  • It provides a mechanism to resolve conflicts between federal and state laws.
  • It supports the division of powers between the federal and state governments outlined in the Constitution.
  • It enables the federal government to implement national policies and programs uniformly across the country.

Without Section 109, there would be confusion about which laws have precedence in cases of inconsistency. The supremacy of federal laws may be undermined if states could freely enact legislation overriding federal laws. Section 109 upholds federal supremacy and is therefore essential to Australia’s federal constitutional arrangements.

How Section 109 Upholds Federal Supremacy

One of the key reasons Section 109 is important is that it upholds the supremacy of federal law. Under Australia’s federal system, the Commonwealth Parliament has the power to make laws on certain specified subjects under Section 51 of the Constitution. The states retain powers over all matters not enumerated under the federal government’s powers.

Section 109 makes it clear that where the Commonwealth enacts a valid law under its constitutional powers, that law will prevail over state laws on the same subject. Without Section 109, states could potentially make laws that undermine or are inconsistent with federal laws.

For example, the federal government has power to make laws on taxation under Section 51(ii) of the Constitution. If a state enacted a law imposing different income tax rates or arrangements to federal income tax laws, Section 109 makes clear the federal law has precedence and the state law is invalid to the extent of the inconsistency.

By upholding federal supremacy, Section 109 prevents fragmentation and supports uniform national laws on subjects such as taxation, corporations law, family law and other areas of federal responsibility.

Key High Court Cases on Section 109

There have been several influential High Court cases that have helped define the operation of Section 109 and reinforced its importance:

Victoria v The Commonwealth (1937)

This case concerned a dispute between the federal government and the state of Victoria over income taxation. Victoria argued its state income tax laws should prevail over federal income tax laws. However, the High Court held that Section 109 required federal taxation laws to prevail as they were inconsistent with the state laws.

O’Sullivan v Noarlunga Meat Ltd (1954)

This case involved inconsistent industrial relations laws at federal and state level. The High Court held the federal law prevailed over the state law to the extent of any inconsistency under Section 109.

Dickson v The Queen (2010)

This case concerned a conflict between Commonwealth and Northern Territory laws on the sentencing of convicted criminals. The High Court found the Commonwealth laws were inconsistent with the Territory laws and therefore invalid under Section 109.

These cases demonstrate how the High Court has consistently upheld the supremacy of federal law using Section 109.

Limitations of Section 109

While Section 109 establishes an important principle, there are some limitations on its operation:

  • It only applies where there is a direct inconsistency between a valid federal law and a state law.
  • It does not apply to reverse inconsistencies – state law prevailing over federal law.
  • The High Court has interpreted it narrowly in some cases.
  • It does not apply to Territory laws, only state laws.

Additionally, Section 109 mainly applies to substantive legislative provisions. When it comes to parliamentary procedures and powers, state sovereignty is largely preserved. Section 109 therefore upholds federal supremacy only to a limited extent.

Controversies Surrounding Section 109

There has been some political controversy about the operation of Section 109 and its impact on states’ rights and powers:

  • Some states have argued Section 109 allows Commonwealth overreach into areas traditionally regulated by states.
  • There are debates around how narrowly or broadly it should be interpreted.
  • Critics argue Section 109 centralises power at the expense of state autonomy.
  • However, proponents argue it is essential to support national consistency and coherence in law-making.

Resolving the appropriate balance of power between the Commonwealth and the states is an ongoing issue in Australian federal relations. Section 109 sits at the centre of this debate.

The Future of Section 109

While Section 109 has been an essential element of Australia’s constitutional framework for over 100 years, there are some proposals to amend or repeal it in future:

  • Some proponents argue adding a “federalist clause” would better protect states’ rights and powers.
  • Another proposal is adding exemptions where federal laws explicitly allow for state inconsistencies.
  • However, removing Section 109 would undermine federal supremacy and severely disrupt Australia’s federal system.

Overall, Section 109 will likely remain a pivotal section defending federal power and national consistency into the future.


Section 109 of the Australian Constitution plays a vital role in upholding federal law supremacy over inconsistent state laws. While its interpretation has varied, High Court rulings have reinforced its importance in preserving national coherence on areas of federal responsibility. Section 109 resolves federal-state inconsistencies in law, promotes national uniformity, and upholds Australia’s federal structure of government. Despite some political controversies, Section 109 remains a fundamental constitutional principle protecting Australia’s federal system.