Professor Anil Kalhan said in a CNN interview on May 30 that if the U.S. Supreme Court rules on President Donald Trump’s travel ban, constitutional issues may not decide the matter.

CNN reported that Attorney General Jeff Sessions vowed to appeal the U.S. Court of Appeals for the Fourth Circuit’s rejection of the travel ban to the U.S. Supreme Court, hours after the panel’s decision was released on May 25.

With the Ninth Circuit soon expected to rule on a second challenge to the travel ban, CNN noted that the legal challenge is based both on constitutional issues and on limits to the president’s authority under statute.

"Because courts are reluctant to reach complicated constitutional questions if they don't have to, the justices could rule on statutory grounds and find that Congress hasn't granted the president the authority to issue an order of this kind," Kalhan said.

Kalhan is an authority on immigration law and comparative constitutional law.