Australian Communist Party v Commonwealth civil liberties grounds, and the proposal was narrowly defeated. Australian Communist Party v Commonwealth Australian Communist Party v The Commonwealth, also known as the Communist Party Case, was a legal case in the High Court of Australia described as "undoubtedly one of the High Court's most important decisions." In a general election held on 10 December 1949, Prime Minister Robert Menzies led a Liberal-Country Party coalition to government pledged to dissolving the Communist Party of Australia. The Party had been banned before: following the Molotov-Ribbentrop Pact, the Party had opposed Australian involvement in the Second World War in 1939, which
Prime Minister of Australia becomes acting Prime Minister in those circumstances. Three Prime Ministers have died in office – Joseph Lyons (1939), John Curtin (1945) and Harold Holt (1967). In each of these cases, the Deputy Prime Minister (an unofficial office at the time) became an interim Prime Minister, pending an election of a new leader of the government party. In none of these cases was the interim Prime Minister successful at the subsequent election. As of , there are seven living former Australian Prime Ministers. The greatest number of living former Prime Ministers at any one time was eight. This has occurred twice: