In a landmark decision, Ontario's highest court Tuesday upheld a lower court decision to legally allow same-sex marriages.

"The existing common law definition of marriage violates the couple's equality rights on the basis of sexual orientation under (the charter)," read the 61-page decision.

The current definition of marriage is invalid and the laws must be changed, said the three judges. The court ordered Toronto city clerks to immediately begin issuing marriage licences.

One of those licences was issued to Michael Leshner and Michael Stark only hours after the ruling. The two men were married in a Toronto ceremony attended by about 50 people.

Both men played a key role in the court case.

Earlier, Lesher, a crown attorney said, "When we get married, we will have lit a match that hopefully illuminates the world."

"Today is the death of homophobia in the courtroom as we've known it," said Leshner.

"Absolute faith in Canadian values" helped him through the long court battle, said Leshner, who encouraged other countries to follow Ontario's lead.

Despite favourable reception in other provinces to the ruling, Alberta's premier said his province remained opposed to same-sex marriages.

"The law in Alberta is very clear, notwithstanding how some people might feel about it, it's very clear. It's as clear as crystal," said Ralph Klein.

"If there is any move to sanctify and legalize same-sex marriages, we will use the notwithstanding clause, period. End of story," he said.

Court offers new definition of marriage

The judgment follows a federal challenge to an earlier Ontario Divisional Court ruling. On July 12, 2002, the court ordered Parliament to alter its definition of marriage to include gay men and women.

According to the Divisional Court, the federal definition of marriage as a lawful and voluntary union between "one man and one woman" violated the Canadian Charter of Rights and Freedoms.

Ottawa appealed the ruling, arguing marriage is based on a universal concept of a union between one man and one woman.

But the Court of Appeal issued its own definition of a marriage: "the voluntary union for life of two persons to the exclusion of all others."

Prime Minister Jean Chrtien said federal Justice Minister Martin Cauchon is still studying the decision. Ottawa has the right to appeal the decision to the Supreme Court of Canada.

Members of gay rights advocacy group EGALE called on Ottawa to respect the ruling and not launch an appeal.

The case appeared before the court after several same-sex couples tried to apply for marriage licences from the City of Toronto.

Ontario now joins Quebec and British Columbia, where courts have held that denying same-sex marriages is unconstitutional.

If the court ruling stands, Ontario would be the first jurisdiction in North America to make gay marriage legal. Both Quebec and Vermont allow gay civil unions.