The Secretary of the Marine Branch of the Department of Commerce has asked for advice on the question whether the coasting trade provisions of the Navigation Act may by legislation be limited in their operation to such parts of Australia as fall outside the seasonal winter zone as defined in the International Convention respecting the load lines drawn at London on the 5th day of July, 1930.

That convention divided the oceans and tidal waters of the world into zones fixed by geographical limits and laid down different obligations upon shipowners in regard to the marking of load lines upon their ships according as the ships are used in the different zones so specified.

Upon consideration of the convention it is found that a seasonal winter zone is delimited in the southern hemisphere. The northern boundary of the southern ‘winter seasonal’ zone, so far as Australia is concerned, is described in Annex II of the International Convention as follows:

From the east coast of South Africa at lat. 30°s along a rhumb line to the west coast of Australia at lat. 35°s, thence along the south coast of Australia to Cape Arid, thence along a rhumb line to Cape Grim, Tasmania, thence along the north coast of Tasmania to Eddystone Point, thence along a rhumb line to the west coast of South Island, New Zealand, at long. 170°E.

The result of this is that the whole of Tasmania, except the north coast thereof, falls within the seasonal winter zone. Similarly, the coast of Western Australia from Cape Leeuwin to Cape Arid is also in that zone.

In order to determine the powers of the Commonwealth to restrict the coasting trade provisions of the Navigation Act in the manner suggested, it is necessary to consider the provisions of section 99 of the Constitution which are as follows:

The Commonwealth shall not, by any law or regulation of trade, commerce, or revenue, give preference to one State or any part thereof over another State or any part thereof.

The proposed discrimination in the general application of the coasting trade provisions of the Navigation Act is based on geographical limits definitely ascertainable by reference to the International Convention respecting load lines. In that Convention the northern boundary of the southern winter seasonal zone is specifically defined in Annex II in the terms quoted above.

That being so the coasting trade provisions would operate in a definitely ascertained part of Australia and would not operate in the rest of Australia. The question then to be considered is whether the application or non-application of the coasting trade provisions to Tasmania and the southern part of Western Australia would amount to a preference.

For the purposes of this opinion it does not seem to be necessary to determine whether the non-application of the coasting trade provisions to any part of Australia amounts to a preference.

The position, if the suggestion of the Secretary, Marine Branch, were carried into effect, would be that the coasting trade provisions would operate in one part of Australia and not in another. I think it would be inevitable that either the part excluded from those provisions, or the part included in those provisions, would have a preference over the other part within the meaning of section 99 of the Constitution.

[Vol. 25, p. 674]