It is a tenable view of Commonwealth v Tasmania that as a matter of ratio decidendi it added nothing to the judicial construction of the Commonwealth's external affairs powers (Constitution ss 51(xxix) and 61) which was not already adumbrated in R v Burgess; ex parte Henry (in 1936) and clearly established in Koowarta v Bjelke-Petersen (in 1982). In this range of cases, attention is concentrated on circumstances in which the Commmonwealth claims power to enact and implement laws having a domestic application within Australia which would not be valid unless they were made in pursuance of an international agreement to which the Commonwealth is a party. There are other circumstances in which the external affairs power will support Commonwealth laws, and these are mentioned in all the Franklin Dam and Koowarta opinions, but hitherto the case illustration of such valid laws has been minimal. It has been hitherto assumed, though not explicitly stated, that international agreements and their implementation in Australia constitute a distinct subdivision or aspect of the legal rules in question.

My comment on Professor Sawer’s paper is confined to three matters: the executive power of the Commonwealth to conclude treaties on behalf of Australia; the relevance of the subject matter of a treaty to the scope of Commonwealth legislative power to implement the provisions of the treaty; and the concept of federalism inherent in the High Court’s decision in the Franklin Dam case.

I want to mention one implication of the views of the minorities in Koowarta and the Franklin Dam case.

Suppose that a State had agreed to the Commonwealth incurring an international obligation (or had even requested it to do so) on a matter such as racial discrimination or the natural heritage. Suppose that, after Australia had incurred the obligation, the State refused to enact legislation needed to fulfil Australia’s international obligation. Or suppose that the State repealed legislation already enacted for that purpose. If the Commonwealth lacked power to implement the international obligation, such State action would result in Australia being left “high and dry” in breach of that obligation.

This possibility of a “backsliding” State, leaving the nation in breach of treaties entered into with State agreement, would be a totally unacceptable position. No doubt the High Court majority in the Franklin Dam case saw this implication of the States’ arguments. The majority’s wide view ofthe external affairs power was the only course available, by means of judicial interpretation, to prevent this from happening.

The legislation enacted to prevent the construction of the Franklin Dam relied on a number of federal legislative powers which included the corporations power and the races power in ss 51(xx) and 51(xxvi) of the Constitution respectively. In contrast to most of the other sections in the Constitution which confer legislative power on the Commonwealth Parliament those sections refer to persons or institutions. In a well-known passage in Stenhouse v Coleman, Dixon J (as he was then) said:

In most of the paragraphs of s.51 the subject of the power is described either by reference to a class of legal, commercial, economic or social transaction or activity (as trade and commerce, banking, marriage), or by specifying some class of public service (as postal installations, lighthouses), or undertaking or operation (as railway construction with the consent of a State), or by naming a recognized category of legislation (as taxation, bankruptcy). In such cases it is usual, when the validity of legislation is in question, to consider whether the legislation operates upon or affects the subject matter, or in the last case answers the description, and to disregard purpose or object.