The Supreme Court of Canada has given the federal government the go-ahead to legalise gay marriage.
Federal Justice Minister Irwin Cotler has said the government will now quickly go ahead with legislation giving same-sex couples the right to marry.
The Canadian federal government had asked the court to consider whether excluding gays and lesbians from legal marriage violated equality rights under the constitution.
The government is proposing legislation which will provide uniformity in respect of civil marriage across Canada. The proposed legislation would change the definition of marriage to the "lawful union of two persons to the exclusion of all others" rather than the "lawful union of one man and one woman."
The federal government referred the proposed bill to the Supreme Court, asking for a non-binding opinion on a number of questions, including whether the government could redefine marriage, whether church groups had to perform the ceremonies and whether the definition of marriage as a union of one man and one woman was against the constitution.
The province of Alberta and religious groups had argued that marriage was a union between a man and a woman.
In its non-binding opinion released today, the court declared that the government had the authority to legislate on marriage and that its proposed definition of marriage as "the lawful union of two persons" would not violate the constitution.
In its ruling the court wrote that "The 'frozen concepts' reasoning runs contrary to one of the most fundamental principles of Canadian constitutional interpretation: that our Constitution is a living tree which, by way of progressive interpretation, accommodates and addresses the realities of modern life. Read expansively, the word "marriage" does not exclude same-sex marriage."
The court exercised its discretion not to answer the government's question on whether the existing opposite-sex requirement for marriage was consistent with the constitution.
"The definition of marriage in five provinces and one territory no longer imports an opposite-sex requirement" the court wrote. "The government has clearly accepted these decisions and adopted this position as its own."
Judges in five provinces and one territory have already overturned the traditional definition of marriage, allowing thousands of same-sex weddings.
The court also ruled that religious officials were protected by the constitution from having to perform gay weddings against their religious beliefs.
At present the Netherlands and Belgium are the only countries that legally recognise same-sex marriages.
The New Zealand parliament yesterday voted to recognize civil unions between same-sex couples, giving them the same legal rights as married couples.
Additional reporting - Reuters