San Francisco Mayor Gavin Newsom touched off a defiant outburst of matrimony 10 days ago when he decided his city would issue marriage licenses to gay and lesbian couples. These marriages -- now more than 3,000 -- are also one of the most flagrant acts of mass civil disobedience in recent years. The freedom-to-marry movement has long grounded its cause in the rhetoric and precedents of the American civil rights movement. As she began her arguments for gay marriage before the Vermont Supreme Court in 1998, lawyer Beth Robinson cited a landmark case from 1948, when the California Supreme Court...