Each state and territory of Australia determines whether or not to use daylight saving time (DST). However, during World War I and World War II all states and territories had daylight saving by federal law, under the defence power in section 51 of the constitution. In 1968, Tasmania was the first state since the war to adopt daylight saving. In 1971, New South Wales, Victoria, Queensland, South Australia, and the Australian Capital Territory also adopted daylight saving, while Western Australia and the Northern Territory did not. Queensland abandoned daylight saving in 1972. Queensland and Western Australia have observed daylight saving over the past 40 years from time to time on a trial basis.