The marriage cases the U.S. Supreme Court has agreed to hear will test an axiom about the court, one that says it prefers to move in small increments rather than big leaps. By next June, the justices could rule narrowly on the constitutionality of allowing same-sex couples to get married. Or they could announce a sweeping ruling that would apply nationwide and remain the law of the land for years to come. "We have no idea if they will ultimately reach the broader issues about gay people and the fundamental right to marry," says Mary Bonauto of Gay and Lesbian Advocates and Defenders, a veteran of the legal battles over gay rights. It's possible the court will find a way to avoid the central issue both cases raise: Does the Constitution's guarantee of equal protection allow the state and federal governments to make legal distinctions between same-sex couples and those of the opposite sex? The court agreed Friday to consider challenges to a law that bars the federal government from recognizing same-sex marriages in the states where they are legal and to California's Proposition 8, the voter-approved initiative that put a stop to marriage in that state for gay couples.