section 109 of the Constitution and its operation in concurrent areas of legislative power

What this dot point is asking

QCAA wants you to know what s 109 says, when it applies, and what the consequence is. Expect a 3-5 mark short response in IA1.

The answer

The text

Section 109 of the Constitution provides:

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.

The Commonwealth's law takes precedence. The state's law is not entirely struck down; only the inconsistent part is invalid. If the Commonwealth law is later repealed, the state law revives.

The three forms of inconsistency

The High Court has recognised three forms.

1. Direct inconsistency: simultaneous obedience impossible

The state law and Commonwealth law impose directly contradictory obligations. A person cannot comply with both.

2. Direct inconsistency: state law alters, impairs or detracts

The state law diminishes the operation of the Commonwealth law, even where literal simultaneous obedience is possible. Clyde Engineering Co Ltd v Cowburn (1926) 37 CLR 466.

3. Indirect (cover the field) inconsistency

The Commonwealth law manifests an intention to cover the field exhaustively. Any state law operating in that field is inconsistent. Ex parte McLean (1930) 43 CLR 472.

Leading cases

Amalgamated Society of Engineers v Adelaide Steamship Co Ltd (1920) 28 CLR 129 (the Engineers Case). Set the modern approach: Commonwealth heads of power are interpreted on their natural meaning. The reserved state powers doctrine and implied intergovernmental immunities were rejected.

Clyde Engineering Co Ltd v Cowburn (1926) 37 CLR 466. The Commonwealth Conciliation and Arbitration Act 1904 (Cth) was held to override a NSW provision affecting working hours that detracted from the Commonwealth scheme.

Ex parte McLean (1930) 43 CLR 472. Established the cover-the-field test for indirect inconsistency.

McBain v Victoria (2000) 99 FCR 116; Re McBain; Ex parte Australian Catholic Bishops Conference (2002) 209 CLR 372. The Federal Court found a Victorian law restricting IVF treatment to married women was inconsistent with the Sex Discrimination Act 1984 (Cth).

Commonwealth v Australian Capital Territory (2013) 250 CLR 441. The High Court struck down the Marriage Equality (Same Sex) Act 2013 (ACT) on the ground that the Marriage Act 1961 (Cth) (as it then stood) was intended to cover the field of marriage. The ACT Act could not operate concurrently. The Commonwealth subsequently amended the Marriage Act 1961 (Cth) in 2017 to recognise same-sex marriage.

Practical operation

Section 109 has been particularly significant in Commonwealth-state conflicts over:

• industrial relations (the Commonwealth's reliance on the corporations power and external affairs power in the WorkChoices Act 2005 (Cth) and Fair Work Act 2009 (Cth));
• anti-discrimination law (the Commonwealth Sex Discrimination Act 1984 (Cth), Disability Discrimination Act 1992 (Cth) and Age Discrimination Act 2004 (Cth));
• marriage law;
• migration and refugee law;
• bankruptcy.

Significance

Section 109 is the central device for managing Commonwealth-state legislative conflict. It implements Commonwealth supremacy in concurrent areas without disrupting state legislative power in residual areas. Without s 109, the resolution of legislative conflicts would require a referendum each time, paralysing the federal system.

Concurrent powers and the limit on section 109

Section 109 only operates where both parliaments have validly legislated in a concurrent area, that is, a subject on which both the Commonwealth (under a head of power in s 51) and the states can make law. It does not apply to exclusive Commonwealth powers (where the states cannot legislate at all) or to residual powers (matters left entirely to the states, where the Commonwealth has no head of power). This is why a s 109 question always begins by confirming that both laws are valid and that they operate in a shared field. If the Commonwealth law is itself beyond power, there is nothing for the state law to be inconsistent with, and s 109 never arises. Framing the answer this way, valid Commonwealth law, valid state law, then inconsistency, signals to the marker that you understand the provision's scope.

The phrase "to the extent of the inconsistency" is also important. Section 109 does not strike down the whole state Act; it suspends only the parts that conflict. The rest of the state law continues to operate, and the suspended part revives automatically if the Commonwealth later repeals or amends its law, as happened after the Commonwealth amended the Marriage Act 1961 (Cth) in 2017. Precision about partial invalidity and revival distinguishes a high-band answer.