WASHINGTON (AP) -- This is an important week in the battle over same-sex marriage as the Supreme Court prepares to hear arguments Tuesday in highly anticipated cases about the right of same-sex couples to marry.

The cases before the court come from Kentucky, Michigan, Ohio and Tennessee, which all had their marriage bans upheld by a federal appeals court in Cincinnati. The justices are being asked to decide whether states have a right to define marriage as the union of a man and a woman, and if so, whether they must recognize same-sex marriages from other places.

Just two years ago, the 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.