These 2 questions are at the heart of a highly anticipated case the Supreme Court is hearing now

The Supreme Court is hearing a huge fight over the legality of gay marriage Tuesday morning, and the justices are exploring two key questions about same-sex unions:

1) Does the Fourteenth Amendment require a state to license a marriage between two people of the same sex?

2) Does the Fourteenth Amendment require a state to recognize a marriage between two people of the same sex when their marriage was lawfully licensed and performed out-of-state?

This will be the second time America's high court has taken up same-sex marriage. The first time, in June 2013, the high court struck down a key provision of the Defense of Marriage Act (DOMA), allowing the US government to recognize same-sex marriages in states where they were already legal.

But in 2013 the high court declined to rule on the broader question about gay marriage: Is there a Constitutional right to gay marriage?

The court's 2013 decision on DOMA has spawned battles across the country over same-sex marriage - including one in Alabama, where courts have issued conflicting rulings leading to an uncertain fate for gay couples.

The Supreme Court will hopefully settle the legal uncertainty over gay marriage after oral arguments on Tuesday. That case will review a decision by the US Court of Appeals for the Sixth Circuit to uphold same-sex marriage bans in Michigan, Ohio, Tennessee, and Kentucky, and it will look at whether those bans violated the Fourteenth Amendment.

That amendment guarantees Americans "equal protection under the law" and the right to "due process of law."

In their petition asking the Supreme Court to hear the case, same-sex couples argued that Kentucky's same-sex marriage ban "marks the same-sex relationships and the families they create as less valuable and less worthy of respect than opposite-sex relationships."

That mark creates a stigma, the petition continued, which is "incompatible with the bedrock Constitutional principles animating the Fourteenth Amendment."

A final decision on the cases is expected by the end of June.