Grier was elected as an alderman in Mimico area in the borough of Etobicoke in 1969. She beat her opponent Gordon Rush by 31 votes. She supported Walter Pitman for the 1970 Ontario NDP leadership race. Pitman came in second to winner Stephen Lewis. She remained in the position until 1985. In 1984 she put her name forward to replace Dennis Flynn as mayor of Etobicoke. Fellow alderman Bruce Sinclair was the eventual winner. She remained as alderman until 1985 when she ran for election in the provincial election.
Provincial
Grier ran as the NDP candidate in the riding of Lakeshore. She ran on a campaign criticizing Tory incumbent Al Kolyn of being lax on environmental issues and on the closing of the Lakeshore Psychiatric Hospital in 1979. She won the election defeating both second place Liberal candidate Frank Sgarlata by 2,037 votes and Kolyn who finished third. In June 1985, she was named as her party's Critic for the Environment, a post which she held until 1990. In December 1986, Grier proposed an Environmental Bill of Rights. Under her proposed legislation, private groups or individuals would be able to take a polluter to court even if they hadn't been personally affected by the pollution. Although the bill was introduced in 1986 and re-introduced in December 1987 and had previously been proposed and supported by the Liberals, the bill failed to move forward through the legislature. The Liberals won a majority in the 1987 provincial election. Grier was re-elected, again defeating challengers Sgarlata and Kolyn. In January 1989, Grier sponsored a private member's bill that proposed to ban the sale of irradiated foods in Ontario. In March 1990, she proposed another private member's bill that would more strictly regulate businesses that stockpiled used tires. This came about due to a large tire fire in Hagersville, Ontario. This idea was adopted by the Liberal government in the form of a tax on tires that was targeted towards recycling programs, although in the short term it meant an increase in tires being sent to landfill.
In government
The NDP won a majority government in the 1990 provincial election and Grier won her riding handily. She was appointed as the Minister of the Environment on 1 October 1990. As Environment Minister, Grier cancelled plans to ship Toronto's garbage to a waste site in Durham, and vetoed a similar plan for Adams Mine in the northern community of Kirkland Lake. The government eventually authorized the creation of three new landfill sites near Toronto, one of which was located on prime farmland. Grier also set limits on the amount of chlorine that pulp and paper mills could dump into rivers and lakes, and rejected one particular downtown Toronto housing project on the grounds that removing industrial waste from the region was prohibitively expensive. She also introduced an Environmental Bill of Rights. The Bill of Rights gave Ontarians the right to sue polluters and it increased the protection for whistleblowing employees. It also created the office of Environmental Commissioner. On 3 February 1993, she was transferred to the Ministry of Health. As Health Minister, Grier supported the listing of generic drugs over large pharmaceutical companies. In 1993, her government made a generous settlement with the province's doctors via an Interim Agreement of Economic Arrangements. Despite strong personal objections, she also introduced user fees for some drug coverage in the summer of 1993. Her government also introduced midwifery as a profession, targeted resources toward community health centres, created a Task Force on the Prevention of Cancer and introduced the Trillium Drug Plan. Notwithstanding her efforts to pursue some traditional NDP policies while in government, Grier generally supported Bob Rae in his efforts to move the party to the political centre. In Bob Rae's memoir, From Protest to Power, he listed Grier as one of his top six closest associates. The NDP were defeated in the 1995 provincial election, and Grier finished third in her bid for re-election in Etobicoke—Lakeshore, losing to Progressive ConservativeMorley Kells.
Cabinet posts
After politics
Afterwards, she was a regular panelist on Fourth Reading, on the TVOntario program Studio 2. In 2000, she along with husband Terry both received honorary doctorates from Ryerson University. Grier was named Visiting Environmentalist at the University of Toronto in 1997, and remains involved in environmental concerns.
