The U.S. Court of Appeals for the Sixth Circuit heard arguments in a challenge to the Trump administration’s bump stock ban for a third time, probing whether the devices fit into the definition of illegal machine guns under federal statutes.

The oral arguments at the Cincinnati-based court come amid a recent circuit split on the issue. Earlier this month, the full Fifth Circuit sided with opponents of the ban in holding that the rapid-fire gun attachments don’t fall under the definition of machine guns. That decision was a departure from earlier rulings from the Sixth, Tenth and D.C. circuits.