NEW ORLEANS >> Bans on gay marriage in three staunchly conservative Southern states were to get a hearing in a federal appeals court Friday — the latest legal battle over an issue expected to be settled by the nation’s highest court.

A three-judge panel of the 5th U.S. Circuit Court of Appeals was scheduled to hear arguments from state attorneys from Texas, Louisiana and Mississippi — all of which passed bans on same-sex marriages — and from the lawyers arguing against the bans.

The cases represent what could be among the last argued in federal court before the U.S. Supreme Court takes up the issue. The high court on Friday was eyeing the possibility of putting gay marriage on its calendar for this term.

Gay marriage is now legal in 36 states and Washington, D.C., as bans on gay and lesbian marriages have been struck down across the nation.

The appellate court in New Orleans took the highly unusual step of consolidating appeals from the three Southern states into one session, which is expected to last about three hours Friday.

Federal district judges in two of the states struck down gay-marriage bans. In Louisiana last September, however, U.S. District Judge Martin Feldman bucked the trend, marking a rare loss for same-sex marriage supporters after more than 20 consecutive rulings overturning bans in other states. His ruling was the first to uphold a state ban after the U.S. Supreme Court struck down part of the federal Defense of Marriage Act in 2013.

“Feldman’s opinion most clearly state’s the opposing view,” said Kenneth Upton, a lawyer for Lambda Legal, a national gay-rights legal organization that will argue on behalf of seven Louisiana gay couples. “In that sense, he’s significant; his decision summarizes the arguments against us.”

Texas voters approved a 2005 state constitutional amendment banning gay marriage, but that amendment was declared unconstitutional last February by U.S. District Judge Orlando Garcia. He allowed the ban to remain in effect pending appeals.

In Mississippi in November, U.S. District Judge Carlton Reeves overturned the state’s definition of marriage as only between a man and a woman. Two lesbian couples and a gay-rights group, Campaign for Southern Equality, sued Mississippi over its anti-gay marriage law and constitutional amendment.

The arguments in the appellate court in New Orleans come on the heels of another defeat in federal court for gay-marriage supporters: In November, the 6th U.S. Circuit Court of Appeals in Cincinnati upheld anti-gay-marriage laws in Kentucky, Michigan, Ohio and Tennessee.

Conversely, four other appeals courts — in Chicago, Denver, San Francisco and Richmond, Virginia — have ruled in favor of gay and lesbian couples.

With a split among the appellate courts, intervention by the Supreme Court to settle gay marriage constitutionality has become very likely.

Between the appellate rulings and the Supreme Court’s decision in October to turn away state appeals, the number of states allowing same-sex couples to marry has risen to 36.