Freedom of interstate trade: s 92

The idea

The words are wide. Trade, commerce and intercourse among the States shall be absolutely free. Cole v Whitfield read that promise down to something workable. Section 92 now guarantees freedom from discriminatory burdens of a protectionist kind rather than freedom from all regulation. It limits Commonwealth and State power alike.

A section 92 problem runs through a fixed sequence. The first question is whether the plaintiff is an interstate trader. The freedom protects no one else. The second is whether the law burdens interstate trade, either in its legal terms or in its practical operation. The third is whether that burden is protectionist, meaning whether it confers a significant competitive advantage on local trade over interstate rivals in the same market. The fourth arises only where the burden is protectionist, and it asks whether a legitimate non protectionist purpose justifies the law under structured proportionality.

One head sits apart from the trade inquiry. A law that restricts the physical crossing of a border engages a separate intercourse limb, which has historically been read more strictly than the trade limb.

Where it comes from

Cole v Whitfield rebuilt the doctrine from the ground up. After Cole the guarantee is freedom from discriminatory burdens of a protectionist kind rather than freedom from all regulation, and it limits Commonwealth and State power alike (Cole at 407 to 408). A burden may appear on the face of the law or only in its factual operation. Tasmania's ban on possessing undersized crayfish caught South Australian fish that were lawfully taken yet unsaleable once landed, and the law survived because conservation gave Tasmanian sellers no market advantage.

Later cases carried the test into harder facts. Castlemaine Tooheys applied it to a facially neutral law. South Australia set a fifteen cent deposit on non refillable bottles and four cents on refillable ones, a scheme even handed on its face that in operation fell hardest on the interstate brewers who used non refillable bottles. Betfair extended the reasoning to a new entrant. Western Australia's ban on betting exchanges bound local operators too, yet its effect was to wall established in State operators off from an interstate arrival. Palmer brought the modern proportionality method to a hard case. The COVID border closure directions burdened interstate trade and intercourse, yet survived because the protection of health was a legitimate purpose that the closure was suited to, necessary for and balanced against.

How it is examined

Section 92 is a live issue in three of the seven finals from 2019 to 2025, and in 2019 it carried twenty marks combined with excise on a single fee. The papers almost always draft the challenged law to treat every trader alike on its face. The marks are not in reciting the sequence. They divide on two moves, the protectionist characterisation and the necessity stage of proportionality, so those are where the words should go.

1. Confirm the plaintiff trades across a border, and if the operator is purely local, say so and move on.
2. Show the burden, and look past the face of the law to how it works in the market.
3. Name any exemption or split that favours local producers. That is the usual protectionist tell.
4. Identify the State's purpose, then press whether a less restrictive measure would have achieved it.
5. Where a fee on goods is involved, characterise it for excise under s 90 as well.

How to argue it

Lead with the sequence and stop at the question that decides the case. The interstate trader will argue that the law burdens its trade, pointing to the legal operation if the terms discriminate and to the factual operation if they do not. The State will respond that the burden confers no significant competitive advantage on local trade in the same market and so is not protectionist. The trader's reply is that the law's practical effect shields in State producers, whether through an exemption that spares them or a distinction that falls on interstate goods. A burden may be protectionist even though it binds some local operators, and even though only some interstate traders feel it, so neither point saves the law by itself.

Where the burden is made out, the argument moves to justification. The State will identify a legitimate non protectionist purpose such as conservation or public health, and the court will largely accept the choice of end. The contest is over means. The trader will point to an equally effective and less restrictive measure, drawn where possible from a comparable jurisdiction that regulated rather than banned. On the balance the trader weighs the extent of the restriction against the importance of the purpose, so a trifling environmental gain will not justify a real barrier while a grave health emergency will. The conclusion should grade its confidence. These cases are often finely balanced, and the pivotal factor is usually necessity. In a border problem note both limbs, and keep them in separate paragraphs because the intercourse limb is stricter.

Practice problems

One hundred exam-style problems across twelve topics. Pick a topic, read the problem, write your own answer in IRAC, then reveal the Pass and H1 exemplars and the examiner's comments. Step through in order or jump to a random one. Nothing you type is saved or sent anywhere.

The trap

The costliest mistake is to treat a facially even handed law as safe. Every paper drafts the challenged law to apply to all traders alike, and the answer lies in its factual operation rather than its terms. Cole and Castlemaine both wore an even handed face and only one survived. Test how the law works in the market, and name the exemption or split that favours local producers.

Two further errors cost marks. The first is treating a legitimate purpose as the finish line, when a genuine conservation or safety aim still fails if a less restrictive measure would have done the job. The second is forgetting the excise twin. The same fee that raises s 92 often raises s 90, so a State charge on goods should be characterised under both.

Key authorities

• Cole v Whitfield — s 92 guarantees freedom from discriminatory burdens of a protectionist kind, binding Commonwealth and State alike, and the protectionist kind step asks whether the burden confers a competitive or market advantage on intrastate trade of the same kind.★
• Cole v Whitfield at 399 — a law burdens interstate trade whether the disability appears in its legal operation or only in its factual operation.★
• Castlemaine Tooheys — a burden is protectionist where it confers a significant competitive advantage on local trade over interstate competitors in the same kind of trade.★
• Castlemaine Tooheys — a facially even handed law still offends s 92 where its practical operation confers the advantage.★
• Castlemaine Tooheys — a burden may be protectionist though it disadvantages only some interstate traders.★
• Betfair — a burden stays protectionist where the ban binds local operators too but shields established in State traders from an interstate new entrant.★
• Betfair at 479 — the burden must be reasonably necessary, not merely appropriate and adapted to a legitimate object.★
• Palmer v Western Australia (2021) 272 CLR 505 — differential burdens on interstate trade and intercourse are tested by structured proportionality against a legitimate non protectionist purpose, and the COVID border closure was justified by the protection of health.★
• Palmer v Western Australia — restrictions on the physical crossing of a border engage the separate and stricter intercourse limb.★