San Francisco officials violated the separation of powers doctrine by assuming for themselves "more power than the Gov., or the Supreme Court, or the Legislature" in issuing marriage licenses to same-sex couples, the state attorney general told the California Supreme Court Thursday, reported the Associated Press.

California Attorney General Bill Lockyer rejected the city's argument that local officials were obligated to grant licenses to same-sex couples because the state Constitution forbids discrimination. He said in a 29-page brief submitted at the request of the California Supreme Court.

Lockyer however told the court that his case against San Francisco isn't about the constitutionality of same-sex marriages but about proper role of public officials.

The seven justices are considering whether Mayor Gavin Newsom had the authority to order his administration to authorise same-sex marriage as the state's Family Code defines marriage as a union between a man and woman.

In papers submitted to the court last week, City Attorney Dennis Herrera's staff argued that there are many examples in state law of public officials, including previous attorneys general, refusing to enforce laws on constitutional grounds.

They also pointed to other state Supreme Courts - most recently in Massachusetts - that already have ruled it unconstitutional to deny gay couples the right to wed.

"San Francisco's officials honored the law; they did not ignore it," he said.

Two weeks ago, justices unanimously ordered local city officials to stop granting marriage licenses to same-sex couples until they consider the case.

Thursday was the deadline for the state and a Christian legal group seeking to invalidate the nearly 4,000 same-sex marriages sanctioned in San Francisco to file legal arguments. The court has said it will hold a hearing as early as May on whether the city overstepped its bounds.