WASHINGTON (AP) — Just two years ago, the Supreme Court struck down part of the federal anti-gay marriage law that denied a range of government benefits to legally married same-sex couples.

The decision did not address the validity of state marriage bans. But courts across the country, with few exceptions, said the ruling's logic compelled them to invalidate state laws that prohibited gay and lesbian couples from marrying.

The number of states allowing same-sex marriage has grown rapidly.

As recently as October, just over one-third of the states permitted same-sex marriage. Now, same-sex couples can marry in 36 states and the District of Columbia.

On Tuesday, the Supreme Court hears arguments in highly anticipated cases about the right of same-sex couples to marry.