The other dispute, with potentially greater impact, tests California's 2008 ban on same-sex marriage. Challengers urged the court to break the ban and rule that gays and lesbians have a constitutional right to marry. But during arguments in March the justices appeared likely to rule in a way that would affect only Californians. Lower federal courts struck down Proposition 8, and it is improbable that a majority on the high court would reverse that trend and endorse the ban.