Supporters of California’s gay marriage ban are asking the judge in a federal trial on the issue to revoke same-sex marriages performed while the practice was legal.

The trial, which heard closing arguments yesterday, is examining whether the state’s 2008 voter-led ban on same-sex marriage violated the US constitution.

Advocates of the ban made their plea when wrapping up their case. They said the order would respect “the expressed will of the people”.

Andrew Pugno, an attorney the ban supporters, said they were not seeking to have the marriages annulled, but wanted the court to rule that government agencies, courts and businesses no longer have to recognise them.

Around 18,000 gay couples married in the state in the few months in which gay marriage was legal. A voter referendum, Proposition 8, struck it down in November 2008, although those couples were allowed to remain married.

Judge Vaughn Walker’s verdict could come within weeks, although both sides have said they will fight the case all the way to the US Supreme Court.

During case testimony, the court heard experts testify that allowing gay marriage would help the mental health of gays and lesbians, give more legal protection to their children, reduce discrimination and give gay couples more political power.

Prop 8 supporters put forward only two witnesses, one of who argued that gays are 12 times more likely to molest children.

But their other witness, from a conservative think tank, conceded under cross-examination that children of gay parents would benefit if their parents were allowed to marry.