TORONTO - Two lesbian women in Toronto have been granted what is believed to be the world's first same-sex divorce, just 15 months after they were married following an Ontario Court of Appeal ruling that permitted gay and lesbian unions in the province.

Superior Court Justice Ruth Mesbur issued an uncontested divorce judgment yesterday and ruled that the Divorce Act definition of spouse as "a man or a woman who are married to each other" is "unconstitutional, inoperative and of no force or effect."

Lawyers for the two women and the federal government agreed during a day-long hearing yesterday that the existing definition of spouse in the Divorce Act violated the Charter of Rights and should be struck down immediately by the judge.

"I don't have a choice. The issue is before me and I must decide," said Judge Mesbur. "I don't have the luxury of waiting around to see what everybody else decides," she added.

The Superior Court ruling is binding only in Ontario. However, it could pave the way for divorces of same-sex couples in other provinces because of the federal government's concessions in this case.

"My client has a lot of sadness," said lawyer Martha McCarthy, who represents one of the two women granted the divorce.

Ms. McCarthy said the couple was in a relationship for several years, although their marriage crumbled within days. "They believed marriage would solve their problems," said Ms. McCarthy.

The two women can only be identified as M.M. and J.H., which are not their actual initials, as a result of an extraordinary order by Judge Mesbur, to protect the privacy of the pair. It is highly unusual for parties in a divorce or child support proceeding to be identified only by initials and contrary to many court rulings that have stressed the importance of openness.

While Ms. McCarthy described Judge Mesbur's decision yesterday as a "technical, check-the-box ruling," the lawyer said it is another indication that "same-sex marriage in Canada is here to stay."

This fall, the Supreme Court will hear arguments on the constitutionality of a draft federal bill to change the definition of marriage and legalize same-sex unions. Courts in Ontario, B.C., Quebec and Yukon have already upheld the right of same-sex couples to marry in decisions that have not been appealed by the federal government.

Judge Mesbur said she would deliver written reasons soon on the specific legal "remedy" she would impose as a result of the unconstitutionality of the definition of spouse in the Divorce Act.

Gail Sinclair, a lawyer for the Attorney General of Canada, argued in court yesterday that the judge should simply strike out any definition of spouse in the Divorce Act. She said the act will be amended after the Supreme Court issues its ruling in the same-sex marriage reference.

Ms. McCarthy and Julie Hannaford, the lawyer for the other woman seeking a divorce, asked Judge Mesbur to rewrite the definition of spouse. The lawyers argued that it should be defined as "two persons" or "two individuals" who are married to each other.