The Tasmanian Dam Case
This is a synopsis of the Tasmanian Dam case which might be interesting for people who are not from Australia. It is just for general information and is written from memory so please excuse any inaccuracies.
The wild rivers of Tasmania possess an enormous amount of energy. Prior to 1983 the Hydro-Electric Commission (HEC) had been building dams across rivers and installing hydroelectric power stations. They then turned their eyes towards the Gordon and Franklin rivers. The Franklin River is a tributary of the Gordon River.
The proposal was to build a dam on the Gordon River below the Franklin River and create a dam which would be 84 metres deep at its toe and would inundate the lower reaches of the Franklin River and flood a couple of archaeological sites in the area which were discovered after the plan to build the dam was announced. The area had been listed on the World Heritage list some few years earlier because of the wilderness character of the area.
Within Tasmania the conservationist movement had been on the rise for some time and the proposal to build the dam became highly contentious. The Tasmanian state government supported the construction of the dam citing economic reasons primarily the need for cheap electricity. The Commonwealth government opposed the development and legislated specifically to prevent the construction of the dam without the consent of a Commonwealth minister.
The Legal Issue
Australia is a federation, that is, a country which is formed by the union of two or more sovereign states which cede their sovereignty to the central (federal) government but do so only to the extent of the agreement which creates the federal government. In other words states retain part of their sovereignty, i.e. rights to make laws, and those rights cannot be taken away other than by force (conquest) or by agreement of the state. The document which contains the agreement between the states is called the constitution. All the states are parties to the constitution but the federal government is not; it is a creation of it.
The constitution defines the division of sovereignty between the states and the federal government by defining the legislative powers of the states and federal governments. There are two ways in which constitutions of this sort can be written. The first is to define the areas in which the federal may legislate and any areas not specifically mentioned are the residual areas over which the states have jurisdiction. The second way is to define the powers that the states do not cede to the federal government and the residual areas make up the jurisdiction of the federal government. Australia's constitution is of the former type.
One of the powers given to the federal government in Australia is the conduct of foreign affairs. The major legal issue of the Tasmanian Dam case was whether the federal government could use the world heritage listing, ie an international treaty to as a basis for legislating in an area covered by the treaty where it would have had no power to legislate had the treaty not been made. In other words, could the federal government expand its own powers at the expense of the states by making an agreement with a foreign power?
The answer in the circumstances of the Dam Case was "Yes".
If you actually want to read the judgment it is here.