← The hardest concepts in Australian law
In one breath
When a valid State law is inconsistent with a valid Commonwealth law, section 109 of the Constitution makes the Commonwealth law prevail and the State law inoperative to the extent of the inconsistency. Inconsistency can arise because the two laws cannot both be obeyed, because one takes away a right the other confers, or because the Commonwealth law was meant to be the complete statement on the subject.
The picture
The eclipse and the sun
Think of a total eclipse. The sun is still there, still burning, as real as it was a minute earlier, but while the moon sits in front of it the light does not reach the ground. When the moon moves on, the light returns without anyone having to relight the sun. Section 109 works in much the same way. A State law that clashes with a Commonwealth law is not destroyed. It is shadowed for as long as the clash lasts, and if the Commonwealth law is repealed or changed, the State law shines again.
The moon can block the sun in two ways. It may cover the whole disc, because the Commonwealth Parliament meant to say everything that is to be said on the subject. Or it may cover only an edge, where the two laws collide on one point. Either way the question is how far the shadow reaches, and that depends on reading both laws closely, not on a feeling that the Commonwealth is the more important government.
Where the picture stops working
An eclipse is a matter of position, whereas inconsistency is a matter of meaning and intention, and Parliament can often settle the answer by saying in the Act that State laws may operate alongside it. The picture also skips the threshold question: section 109 matters only if both laws are valid in the first place.
How it really works
- 1Place the rule. Section 109 is constitutional, so it applies across the country, but it deals with State laws; the self-governing Territories sit under their own self-government Acts.
- 2Check that both laws are valid. If the Commonwealth law is outside its head of power, there is nothing for the State law to yield to.
- 3Ask whether the inconsistency is direct. Could a person obey both laws at once? Does one law take away a right that the other confers?
- 4If not, ask whether the Commonwealth law is meant to be exhaustive, so that it “covers the field”. Read its text, purpose and subject, and look for any statement about whether State laws may operate beside it.
- 5Apply the result. The State law is inoperative to the extent of the inconsistency and only while it lasts. If the Commonwealth law is repealed, the State law may operate again.
Why people get it wrong
- Thinking the State law is wiped out for good. It is inoperative while the clash lasts, and it can revive.
- Assuming that any overlap is an inconsistency. Two laws may touch the same conduct and be obeyed together, if the Commonwealth law does not claim the whole subject.
- Treating the Commonwealth as the winner every time. Priority arises only where both laws are valid and truly conflict.
- Deciding by the importance of the subject. The test is the meaning and purpose of the Commonwealth law.
- Forgetting the words “to the extent of”. Parts of the State law that do not clash may keep operating.
A worked example
The facts are invented
A valid Commonwealth Act sets out the labelling required for packaged pet food and states that it is a complete code on the subject. A State law adds a further warning panel that the Commonwealth Act does not require. A producer could, physically, comply with both. Even so, because the Commonwealth Act is meant to be the whole law on labelling, the State warning requirement is inoperative while the Commonwealth Act stands.
Change the facts. The Commonwealth Act deals only with ingredient lists, while the State law regulates the print size of the best-before date. The two sit side by side, so nothing is inconsistent. Change them again: the Commonwealth Act is repealed. The State warning requirement, which was only suspended, operates again without new State legislation.
Try it
A Commonwealth Act is a complete code for the labelling of packaged pet food. A State law adds a warning panel that the Act does not require, although a producer could comply with both. What is the best view?
Landmark authorities
Read the sources themselves; this list is a starting point.
- Clyde Engineering Co Ltd v Cowburn, (1926) 37 CLR 466
- Ex parte McLean, (1930) 43 CLR 472
- Carter v Egg and Egg Pulp Marketing Board (Vic), (1942) 66 CLR 557
- Telstra Corporation Ltd v Worthing, (1999) 197 CLR 61
Where to go next
Courses
Dictionary
More hard concepts in Australia law
- The separation of judicial power and the Boilermakers principle (Constitutional law)
- The implied freedom of political communication (Constitutional law)
- The guarantee of acquisition on just terms (Constitutional law)
- The Commonwealth’s heads of power (Constitutional law)
- State and federal courts: Wakim and Kable (Constitutional law)
This page is an educational overview. It is not legal advice and not a substitute for the sources: the statute, the rule, the case itself. Australia is a federation: the Commonwealth, the six States and the Territories each make law, and the High Court is the final court for all of it. The common law, by contrast, is one law across the country. Each page says whether the rule is constitutional, federal or common law shared by every jurisdiction, or State-by-State legislation that varies, and flags where the States and Territories differ. Each page states the usual formulation of the rule and names landmark decisions; check the primary sources of your own jurisdiction before relying on any rule.