The 4th U.S. Circuit Court of Appeals, which will hear oral arguments this week at the start of its annual term, will be under the microscope as senators, legal experts, and conservative and liberal groups watch to see if five vacant judgeships will trigger an ideological shift in one of the nation’s most conservative federal appellate benches.

“I think the ideological balance of that court is completely in play,” says Jay Sekulow, chief counsel of the conservative American Center for Law and Justice. “I think this is the most important judicial nominee fight that we’ve had in decades, and you’ve got an entire court of appeals hanging in the balance.”