Prime Minister of New Zealand signed a number of international treaties. In 1967, Keith Holyoake became the first New Zealand prime minister to select candidates for the position of governor-general without any involvement of the British government. Holyoake advised the monarch, Queen Elizabeth II, to appoint Sir Arthur Porritt, the first New Zealand–born governor-general. After the mixed-member proportional (MMP) system was introduced in 1996, prime ministers have had to manage minority governments. The skill of MMP management was exemplified by Helen Clark's nine years as prime minister (1999–2008), when her Labour Party remained in power thanks to a range of confidence and supply agreements with
Helen Clark of Labour and Deputy Prime Minister in August 1989. As Health Minister, Clark introduced a series of legislative changes that allowed midwives to practice autonomously. She also introduced the Smoke-free Environments Act 1990, a law which restricted smoking in places such as workplaces and schools. As Deputy Prime Minister, Clark chaired the Cabinet Social Equity Committee, and was a member of several other important Cabinet committees, such as the Policy Committee, Economic Development and Employment Committee, and Domestic and External Security Committee. From October 1990 until December 1993 Clark held the posts of Deputy Leader of the Opposition, Shadow spokesperson