SAN FRANCISCO -- Some state lawmakers added their voices Monday to the chorus calling on California's highest court to overturn the prohibition on same-sex marriage approved by voters last week.

Forty-four members of the California Legislature filed a friend-of-the-court brief in support one of the three lawsuits seeking to invalidate Proposition 8.

The case, brought on behalf of gay couples who have not yet married, argues the ban should be tossed out because voters did not have the authority to make such a dramatic change in state law.

Thousands protested the gay-marriage ban California voters approved of on Election Day outside the Capitol on Sunday.

"They gave rights and then they took them away from people and that's just not right either," said Andrea Dickson, who opposes Proposition 8.

The brief argues that the gay marriage ban improperly usurped the state Supreme Court's duty to protect minority groups from discrimination. Proposition 8 overturned the court's May decision that legalized same-sex marriage.

Senate President Pro Tempore Don Perata and Assembly Speaker Karen Bass are among the signers.

Bass said in a news release issued Monday that "the inalienable right to equal treatment under the law must be protected and upheld."

Also Monday, the Campaign for California Families asked the court for permission to become an official party to all three cases, which currently name only the state health department and Attorney General Jerry Brown as respondents.

"Every voter should be offended that 40 Democrats at the state Capitol have decided to declare war on the democratic vote of the people," said Randy Thomasson, of the Campaign for Children and Families.

The conservative group, which unsuccessfully sought to get a gay marriage ban on the ballot that also would have stripped same-sex couples of domestic partner benefits, said in its motion to intervene that state officials would not adequately defend the rights of voters.

"I think it is very unlikely that the judges are going to agree with the Democrats or the gay activists," Thomasson said.