The Constitution is not a math problem, but numbers can play a role in the Supreme Court’s calculations.

When the court struck down bans on interracial marriage in 1967, such unions were still illegal in 16 states.

When the court struck down laws making gay sex a crime in 2003, 13 states still had antisodomy measures.

Should the court take up the question of same-sex marriage this term or next, as it seems likely to, the unions will be against the law in no more than 15 states.