The 18,000 gay and lesbian couples who legally married in California last year may find out today if they are valid.

The state’s Supreme Court will begin hearing arguments about the validity of Proposition 8, a ballot measure passed by voters in November that ended same-sex marriage.

Vigils were held across California yesterday by supporters of equality for gay and lesbian people.

The court may reveal today its stance on Prop 8 and the legal status of those married same-sex couples.

The hearing will be televised and can be seen here. It begins at 5pm GMT.

In May 2008 the California Supreme Court ruled against a previous Proposition approved in 2000 that defined marriage in the state as between a man and a woman.

The court ruled that laws that treat people differently based on their sexual orientation violate the equal protection clause of the California Constitution and that same-sex couples have the same fundamental right to marry as other Californians.

Proposition 8 challenged this ruling by explicitly denying gay people the right to marry.

Dozens of groups have filed amicus curiae or “friend of the court” briefs arguing that Proposition 8 drastically alters the equal protection guarantee in California’s Constitution, and that the rights of a minority cannot be eliminated by a simple majority vote.