Nicholas Pengelley and Sue Milne present a completely updated guide to researching law in Australia. The Commonwealth of Australia is a common law jurisdiction; a federation within the British Commonwealth, with Queen Elizabeth II as its head of state. The Queen is represented in Australia by a Governor-General at the national level, and in each of the six states by a Governor. The Australian Constitution, embodying the doctrine of separation of powers, prescribes the authority of the executive, legislative and judicial arms of government. It was enacted British Act of Parliament in 1901 and the then separate colonies were united as states of one country. As well as the six states there are three self-governing territories (one of them, the Australian Capital Territory, is the site of the federal seat of government, Canberra) and a number of external territories – islands in the Indian and Pacific Oceans, and the Australian Antarctic Territory.