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 words of s. 109 make it plain that it deals only with inconsistency between laws. It does not deal with inconsistency between powers: O'Sullivan v. Noarlunga Meat Ltd. [2] . It does not deal directly with inconsistency between executive or judicial acts done under a power conferred by a federal law, on the one hand, and acts of that kind done under a State law, on the other hand. If a federal law validly confers a power which is intended to be exclusive, so that no one else can do the same thing, s. 109 directly operates, with the result that a State law conferring a power to do that thing would be invalid. However the federal law may reveal an intention that although the power which it confers is not exclusive, an exercise of that power will be exclusive; in that event, s. 109 will give paramountcy to the law under which the power is exercised, with the result that State law cannot validly operate once the power has been exercised. This was explained, in relation to awards, in Ex parte McLean [3] , by Dixon J. who said [4] :
If the Act means not only to give the determinations of the arbitrator binding force between the disputants, but to enable him to prescribe completely or exhaustively what upon any subject in dispute shall be their industrial relations, then s. 109 would operate to give paramountcy to these provisions of the statute, unless they were ultra vires, and they in turn would give to the award an exclusive operation which might appear equivalent almost to paramountcy.
The argument on behalf of the applicants in the present case was based on two cases in which this principle was discussed. In Victoria v. The Commonwealth [5] it was held that there was no inconsistency between a State Act which empowered a State authority to remove a ship sunk in Victorian waters, and a Commonwealth Act which made similar provision for the removal by a Commonwealth authority of a ship sunk on or near the coast of Australia. There is no necessary inconsistency in two authorities having power to remove the same wreck, and it was held that the power given to the Commonwealth authority was not intended to be exclusive. However, a conflict might have arisen if both authorities had simultaneously attempted to remove the wreck. The members of the Court expressed rather different views as to the outcome of such a situation, but it may be concluded that if the Commonwealth Act considered in that case had revealed an intention to make the exercise of the power by the Commonwealth authority exclusive, the effect of s. 109 would have been to give paramountcy to the Commonwealth law over the State law, and thus to render invalid the State law to the extent to which it authorized any action which would interfere with the exercise of power by the Commonwealth authority: see the discussion at pp. 626, 628, 630-631 and 635-637. Similarly, the fact that a Commonwealth statute and a State statute both authorized the acquisition of eggs would not necessarily mean that the Commonwealth statute excluded the operation of the State power, but if both the Commonwealth and the State sought to acquire the same eggs, there would be a conflict in the operation of the power, and in that case s. 109 would give paramountcy to the Commonwealth statute which would, no doubt, be construed as meaning that the Commonwealth power of acquisition was to supersede any attempted acquisition by the State authority: Carter v. Egg and Egg Pulp Marketing Board (Vict.) [6] . In cases such as this the first question is what is the meaning and effect of the Commonwealth law under which the power is exercised; only when the effect of a valid Commonwealth law has been determined, is it possible to consider whether a State law is inconsistent with it.
1. (1956) 95 C.L.R. 177, at p. 183.
2. (1930) 43 C.L.R. 472, at pp. 484-485.
3. (1930) 43 C.L.R., at p. 484.
4. (1937) 58 C.L.R. 618.
5. (1942) 66 C.L.R. 557, at pp. 574-576.