San Francisco ? A widely anticipated federal trial over the constitutionality of California’s ban on same-sex marriage opened Monday, with lawyers and witnesses debating the meaning of marriage and sexual orientation and gay couples testifying about the humiliation of being denied matrimony.

While supporters of same-sex marriage demonstrated in the fog outside and the U.S. Supreme Court wrangled with whether to allow broadcast of the trial, the case moved along briskly, with sometimes tearful testimony from two gay couples who brought the lawsuit and an explanation of the roots of marriage by a Harvard historian.

The lawsuit charges that Proposition 8’s reinstatement of a ban on same sex-marriage violates U.S. Constitutional guarantees of equal protection and due process. The constitutionality of the ban is expected to eventually reach the U.S. Supreme Court as a landmark case.