Advice to the Governor-General is given by the prime minister and, also by convention, the prime minister's advice is ordinarily to be followed. There may, however, be circumstances in which a Governor-General has to act, or may choose to act, without or against prime ministerial advice. These include a situation where, following a general election, no party has an overall majority in the House of Representatives, so that the Governor-General has to choose a prime minister without a prime minister to give advice. Such discretions are known as the Governor-General's "reserve powers", but it is uncertain what they include and it remains highly controversial that in 1975 a Governor-General dismissed a prime minister who, in the Governor-General's opinion, was unable to obtain supply.