First elected to parliament at the 1990 Fremantle state by-election, McGinty became a minister in the government of Carmen Lawrence in 1991. He was made the Minister for Housing, Construction, Services and Heritage. With the exception of the Services, which he relinquished soon after taking the Environment portfolio in late 1992, McGinty held all these portfolios until Labor's defeat at the 1993 state election. McGinty became leader of his party in 1994, succeeding Ian Taylor, only to be replaced by Geoff Gallop prior to the 1996 state election. The leadership change was due to a mutual decision between McGinty and Gallop in response to the fact that McGinty could not make a dent on the popularity of Liberal Premier Richard Court in opinion polls. Gallop had been McGinty's deputy and the two swap leadership roles with McGinty now becoming Gallop's deputy. McGinty however was replaced as deputy after the 1996 election by Eric Ripper. After Labor returned to power at the 2001 state election, McGinty was again on the treasury bench. He became the Attorney-General, Minister for Justice, Legal Affairs, Electoral Affairs, Peel and South West. A reshuffle in 2003 saw McGinty remain Attorney-General and Minister for Electoral Affairs, as well becoming Minister for Health. He retained these portfolios until Labor's defeat at the 2008 state election. McGinty had stood down as ALP leader without having a chance of presenting his case to the people of why he should be Premier at the 1996 election. As minister in the Gallop Government the prospect of him finally becoming Premier became a real possibility when Premier Gallop stood down in 2006. McGinty however did not nominate to replace Premier Gallop as factional deals had ensured Alan Carpenter becoming the next ALP leader and thus Premier. During his time as Attorney General, Mr McGinty was recognised as a reformer. Achieving 'one vote one value' for the Legislative Assembly and Gay and Lesbian equality in the laws of Western Australia are widely seen as the hallmarks of his tenure. In addition, he established many new legal institutions, including the Corruption and Crime Commission, the State Administrative Tribunal and the Court of Appeal. As Health Minister, he was responsible for banning smoking in pubs and clubs, and for the health blueprint which has seen the creation of Fiona Stanley Hospital and the new Perth Children's Hospital as well as significant new facilities at all major metropolitan hospitals. In recognition of his contribution to law reform and the Parliament of Western Australia, Mr McGinty was made a Member of the Order of Australia in 2013.
Retirement
On 3 April 2009, McGinty announced his retirement from politics. This triggered a by-election for his district, in which Labor suffered a 16-point swing that delivered the seat to The Greens candidate, Adele Carles.
