A lesbian couple apply for a marriage licence in Wisconsin.

THE city of San Francisco made history by becoming the first civil authority in America to officially marry gay couples in open defiance of laws banning the practice.

The city, under the orders of its liberal new Mayor Gavin Newsom, officially married at least 15 gay couples and issued marriage licences to around a dozen others in a move that infuriated traditionalist groups.

The dramatic and landmark move in California came as lawmakers in Massachusetts struggled to thwart a court ruling legalising same-sex marriages in the eastern US state.

The two cases, on opposite sides of the country, served to highlight the bitter struggle in the US over the issue of gay unions, which looks set to figure prominently in campaigning for November’s presidential election.

The first couple to have their same-sex union officially blessed under Mr Newsom’s challenge to a state law that bars same-sex marriages was a pair of elderly lesbians who have been together for half a century.

A city official officiated at the wedding of Del Martin, 83, and 79-year-old Phyllis Lyon after Newsom late on Wednesday ordered his staff to issue marriage licences to gay couples.

City official Mabel Teng officiated at the ceremony for Martin and Lyon, exchanging the traditional phrase of “husband and wife” for “spouse for life”.

“This is a very significant day for Del and Phyllis and for all of us witnessing this historic ceremony,” Ms Teng said.

So many couples took the city up on its surprise offer that, by late afternoon, overwhelmed officials told new applicants to return yesterday. In all, the clerk’s office issued 95 marriage licenses to same-sex partners, and 87 couples took their vows on the spot.