The first US federal court case to determine whether states are allowed to ban same-sex marriages has opened in San Francisco, California.

美国加州联邦法院第一次判定其是否有权禁止同性恋婚姻案件在旧金山展开审理。

Two gay couples are testifying at the trial

Any ruling reached is expected to be challenged, possibly taking the case all the way to the US Supreme² Court.

A Supreme Court ruling would determine the fate of gay marriages nationwide, without the possibility of appeal上诉.

The suit, filed by two gay couples, challenges Proposition 8 - a ban on gay marriage in the state of California.

The law amended修订，改进 California's constitution to restrict限制，拘束 marriage to a union between a man and a woman.

Supporters of the challenge are comparing it to landmark⁴ cases which ended segregation⁵隔离，分离 in US schools and overturned a ban on interracial人种间的 marriage, the BBC's Rajesh Mirchandani reports.

They say the Constitution enshrines铭记，珍藏 the right to marry but, by limiting it to heterosexual异性恋的 couples, it discriminates⁶ against歧视，排斥 gay people.

'Social fabric⁸'

Backers of Proposition 8 say the federal case is the latest attempt to overturn what they say is the will of the people as expressed by the 52% who backed the amendment⁹ in a 2008 referendum公民投票，全民公决.

Chief US District Judge Vaughn Walker will have to decide whether the ban on same-sex marriage in California is constitutional.

The case is being argued by high-profile lawyers Theodore Olson and David Boies.

Proceedings¹⁰ opened on Monday with testimony¹¹ from two plaintiffs原告 in the case, Kristin Perry and Sandra Stier, who wed¹ in California 2004 only to have their union later declared invalid无效的.

Ms Stier said that being allowed to wed her partner would "provide me with a sense of inclusion包含 in the social fabric社会结构 of the society I live in".

"I want our children to feel proud of us," she told the court. "I don't want them to worry about us."

Kristen Perry said: "I want it to happen to me. The state isn't letting me feel happy."

Paul Katami and his partner Jeffrey Zarrillo described slights in gay life that ranged from being pelted¹³ with用……扔某人，质问 stones and eggs in college to the awkwardness笨拙，尴尬 of checking into a hotel and not being able to clarify the relationship.

"Being able to call him my husband is so definitive," Mr Katami said. "There is no subtlety微妙，敏锐 to it. It is absolute."

Supporters of Proposition 8 will argue California does not discriminate⁷ against the gay community, as the current law allows them to get married - as long as they wed a partner of the opposite sex.

"This lawsuit¹⁵ is an attempt by Judge Walker to put the voters of California on trial, and it's wrong," said Brian Brown, director of the National Organization for Marriage, which opposes gay marriage.

"I think our founding fathers would be rolling over in their graves if they heard that the constitution guarantees the right to redefine重新定义 marriage," he told AFP news agency.