SAN FRANCISCO (AP) - California Gov. Arnold Schwarzenegger is holding firm in his refusal to defend the state's same-sex marriage ban in court.

Lawyers for Schwarzenegger said in a letter Wednesday that the governor has authority to refuse to appeal a federal judge's ruling that overturned Proposition 8. The letter was filed with the California Supreme Court.

It came in response to an effort by a conservative legal group to persuade the court to force Schwarzenegger and Attorney General Jerry Brown to challenge the Aug. 4 ruling that declared the voter-approved ban unconstitutional.

Proposition 8's sponsors have appealed. But doubts have been raised about whether its members have the authority to do so because as ordinary citizens they are not responsible for enforcing marriage laws.