Supreme Court judges sat to hear arguments last night in favour of abolishing Proposition 8 in California.

Prop 8 was passed in November 2008, overturning a state Supreme Court ruling in May that legalised gay marriage in the state.

After hearing arguments from gay rights lawyers, the seven judges have 90 days to decide whether the proposition was valid and if the 18,000 same-sex couples who wed between May and November can remain legally married.

Forty-three friend-of-the-court briefs, representing hundreds of religious organizations, civil rights groups, and labor unions, and numerous California municipal governments, bar associations, and leading legal scholars, were filed in the case, urging the court to strike down the initiative

Supporters of gay marriage have argued that Prop 8 is unconstitutional and discriminatory as it defines marriage as being between a man and a woman.

The issue is over whether a voting majority can overrule minority rights previously recognised by the court, as it had previously declared that gays and lesbians have a constitutional right to marry.

“Proposition 8 jeopardises not just the right of same-sex couples to marry, but the rights of all Californians to be treated as free and equal citizens of this state,” said Shannon P Minter, legal director of the National Center for Lesbian Rights, who argued the case before the court.

“Our constitution is based on the principle that majorities must respect minority rights.

“But if a majority can change the constitution to take away a fundamental right from one group, then it can take away fundamental rights from any group. Our government will have changed from one that respects minority rights to one in which the power of the majority is unlimited.”

The legal challenge was filed by the NCLR, the American Civil Liberties Union and Lamba Legal on November 5th, after Prop 8 was passed.

Jennifer C Pizer, marriage project director for Lambda Legal and co-counsel in the legal challenge said: “It is simply wrong – legally and socially – to short-circuit the California constitution and its equal protection guarantees.

“This is a radical attempt to strip a cherished constitutional right from just one targeted minority group and then to stop the courts from doing their most basic job of upholding the constitutional promise of ‘liberty and justice for all’.”

According to Equality California, the case is unprecedented because no other initiative-amendment has successfully taken away a fundamental right only for a particular minority.

The groups argue that Prop 8, which was a voter initiative, is invalid because it improperly attempts to undo the California constitution’s core commitment to equality and deprives the courts of their essential role of protecting the rights of minorities.

According to the constitution’s text, such changes can only be pursued, if at all, through the constitutional revision process, not with an initiative.

Lawyers also argued that other minority groups could find themselves affected by Prop 8, as it could lead to them becoming the targets of initiative campaigns designed to remove their rights.