In a recent decision, the U.S. Supreme Court upheld the view that gays and lesbians are an identifiable class in the eyes of the law -- a characterization that anti-gay-marriage forces have vigorously fought and that attorneys challenging California's Proposition 8 see as a crucial element of their case.

In a Tuesday letter to U.S. district judge Vaughn R. Walker, Theodore J. Boutrous, who argued against Prop. 8 in the high-profile case Perry v. Schwarzenegger alongside lead plaintiffs' attorneys Ted Olson and David Boies, wrote that "sexual orientation is not merely behavioral," and that, as the Supreme Court found Monday in Christian Legal Society v. Martinez, "there is no distinction between gay and lesbian individuals and their conduct."