The California Supreme Court will today hear final arguments from same-sex couples who want access to civil marriage in the state.

Attorneys will argue that California violates its own constitution by denying same-sex partners the right to marry.

The California Supreme Court agreed to hear the case in 2006 after the California Court of Appeal reversed a decision by San Francisco Superior Court Judge Richard A. Kramer finding that barring same-sex couples from marriage unconstitutionally discriminates on the basis of sex and violates the fundamental right to marry.

California has the highest number of same-sex couples in America.

The case currently before the court has attracted more “friend of the court” briefs than any other case in recent memory.

Specifically, the California Supreme Court has received 45 such briefs from 145 different organisations hoping to persuade it to decide the case in their favour.

The state’s Republican Governor, Arnold Schwarzenegger, has twice vetoed a bill allowing gay marriages, saying voters and the state Supreme Court, not legislators, should decide the issue.

A brief filed by the city and county of San Francisco claims that by denying marriage to gay couples, “the state segregates them and their families from the rest of society, continuing to marginalise them.”

The brief also said that the ban “reinforces in the public mind the already entrenched inferior status of lesbians and gay men.”

San Francisco caused a stir in 2004 by issuing marriage licenses to same-sex couples, which were later voided by the state.

In 2005 Superior Court Judge Richard Kramer ruled that the ban serves no rational purpose, and that it is unconstitutional because it denies same-sex couples equality.

This ruling was later overturned by the Court of Appeal, who concluded that the ban does not violate constitutional rights, and only legislators can define the institution of marriage.

The Court of Appeal considered whether the constitution offered a fundamental right to “same-sex marriage.”

The San Francisco brief said that this goes against established precedent.

It said: “Past courts have not treated marriage claims by interracial couples as involving the right to ‘mixed race marriage.'”

The brief issued by the couples urged the court that “marriage should [not] remain exclusively heterosexual merely because it always has been so.”

The Attorney General’s office is duty-bound to defend state law, and so will be arguing against same-sex marriage.

Former assemblyman Larry Bowler, a proponent of the ban, said last year: “We fully expect the California Supreme Court to destroy marriage for a man and a women.

“At least four justices on that San Francisco bench are against the broad majority of California voters, who want marriage preserved and protected.

“The high court could deal a low blow to the voters by creating so-called same-sex marriages in late 2007 or early 2008.”