Following is a timeline of events leading to the Supreme Court of Canada's opinion on questions concerning same-sex marriage.

Jan. 27, 2005: Federal Justice Minister Irwin Cotler says he will introduce legislation extending marriage to include same-sex couples when Parliament returns from its winter break on Jan. 31.

Jan. 23, 2005: Conservative Leader Stephen Harper tells CTV's Question Period that Prime Minister Paul Martin's threat to call an election over same-sex marriage is aimed at Liberal backbenchers. Harper says the PM is facing "a lot of opposition in the Liberal party."

Jan 21, 2005: Prime Minister Paul Martin says the issue of same-sex marriage is so important to him, he'd be willing to call an election over the issue. Martin said he would do so to uphold the Charter of Rights and Freedoms.

Jan 19, 2005: Toronto's Catholic Cardinal Aloysius Ambrozic urges Martin to not pass same-sex marriage, and to use the Constitution's notwithstanding clause to override the Charter.

Dec. 9, 2004: Supreme Court announces that Ottawa has the power to redefine marriage to include same-sex couples, but says religious officials can't be forced to marry them.

Nov. 26, 2004: Ontario Court of Appeal rules that gays and lesbians are entitled to survivors' benefits under the Canada Pension plan dating back to 1985.

June 2004: A married lesbian couple in Ontario files the first same-sex divorce petition in Canada. A judge grants the divorce in September.

Jan. 26, 2004: Prime Minister Paul Martin adds a fourth question asking whether the traditional definition of marriage between a man and a woman is constitutional.

July 16, 2003: Prime Minister Jean Chretien asks the Supreme Court of Canada to answer three questions: Is a draft bill to allow same-sex marriage within Parliament's jurisdiction? Does the draft legislation respect the Charter of Rights and Freedoms? Must all religious institutions perform same-sex marriages?

June 10, 2003: Ontario's Court of Appeal upholds a lower court ruling that allows same-sex marriage. It orders Toronto city clerks to begin issuing marriage licences to same-sex couples right away. The case had been fought for by Michael Stark and Michael Leshner, who were married hours later.

May 1, 2003: B.C.'s Court of Appeal says limiting marriage to heterosexuals violates equality rights. It gives Ottawa two years to recognize same-sex couples before the judgment takes effect.

July 12, 2002: The Ontario Superior Court says banning same-sex marriage is unconstitutional and violates the Charter or Rights and Freedoms.

April 11, 2000: The federal government passes Bill C-23. It extends the same social and tax benefits to same-sex couples that that common-law couples have.

March 16, 2000: Alberta's government passes Bill 202, stating the province would use the notwithstanding clause if a court redefined marriage to include same-sex couples.

June 8, 1999: A vote in the House of Commons to preserve the definition of marriage as a union between a man and a woman passes 216-55.

November 1992: The government removes a law prohibiting gays, lesbians and bisexuals from serving in the military.

1988: The NDP's Svend Robinson publicly announces he's gay, making him the first Canadian MP to do so.

Feb. 5, 1981: More than 300 men are arrested after police raid gay bath houses in Toronto. The next night, thousands march through downtown streets to protest the arrests.

December 16, 1977: Quebec becomes the first province to include sexual orientation in its Human Rights Code. Under the code, it is illegal to discriminate against gays.

1979: The Canadian Human Rights Commission recommends adding "sexual orientation" to the Canadian Human Rights Act.

1969: Prime Minister Pierre Trudeau passes Bill C-150, an amendment to the Criminal Code that decriminalizes homosexuality.