The votes have not all been counted yet, but that has not stopped lesbian and gay rights groups filing lawsuits challenging the validity of Proposition 8.

Californian voters backed the ballot measure yesterday.

With 96.6% of precincts reporting, 5,235,486 or 52.2% are in favour of eliminating the right of same-sex couples to get married.

4,800,656 (47.8%) voted no.

Prop 8 was placed on the ballot in response to a California Supreme Court ruling in May allowing same-sex marriages.

Today the American Civil Liberties Union, Lambda Legal and the National Centre for Lesbian Rights filed a writ petition before the California Supreme Court today urging the court to invalidate Proposition 8.

The petition charges that Proposition 8 is invalid because the initiative process was improperly used in an attempt to undo the constitution’s core commitment to equality for everyone by eliminating a fundamental right from just one group – lesbian and gay Californians.

Proposition 8 also “improperly attempts to prevent the courts from exercising their essential constitutional role of protecting the equal protection rights of minorities.”

According to the California Constitution, such radical changes to the organising principles of state government cannot be made by simple majority vote through the initiative process, but instead must, at a minimum, go through the state legislature first.

“The California Constitution itself sets out two ways to alter the document that sets the most basic rules about how state government works,” the groups said in a statement.

“Through the initiative process, voters can make relatively small changes to the constitution.

“But any measure that would change the underlying principles of the constitution must first be approved by the legislature before being submitted to the voters.

“That didn’t happen with Proposition 8, and that’s why it’s invalid.”

The lawsuit was filed today in the California Supreme Court on behalf of Equality California and 6 same-sex couples who did not marry before Tuesday’s election but would like to be able to marry now.

“Historically, courts are reluctant to get involved in disputes if they can avoid doing so,” said Shannon Minter, Legal Director of NCLR.

“It is not uncommon for the court to wait to see what happens at the polls before considering these legal arguments. However, now that Prop 8 may pass, the courts will have to weigh in and we believe they will agree that Prop 8 should never have been on the ballot in the first place.”

The groups said they are confident that the state will continue to honour the marriages of the 18,000 lesbian and gay couples who have already married in California.