A California advocacy group vowed Tuesday to overturn the state's ballot initiative banning same-sex marriages, which was upheld by the state's Supreme Court today.

While strongly criticizing the court's ruling upholding Proposition 8, a constitutional amendment banning gay marriage narrowly approved by California voters last fall, Equality California (EQCA) said it would focus its efforts on overturning the law in 2010.

"Today's ruling is a miscarriage of justice," EQCA Marriage Director Marc Solomon said in a memo. "No minority group should have to defend its right to equality at the ballot."

"We believe, as do the majority of our members, that 2010 is the best time to return to the ballot to repeal Prop. 8," Solomon added. "We must take full advantage of the momentum and commitment people now have to do the work required on the ground."

Solomon acknowledged the difficulty in reversing last fall's vote, but pledged to wage a winning campaign with allies throughout the state in order to reinstitute legal gay and lesbian marriages in California.

The California Supreme Court upheld the legality of Prop. 8 on Tuesday, but said that the some 18,000 same-sex couples married before the proposition passed will still be recognized as married by the state.

Similarly, another group, Californians Against Hate, said in a statement that, "Next year we will win back our rights."