Chief Justice John Roberts Jr. and Justices Brett Kavanaugh and Amy Coney Barrett may hold the key to whether the U.S. Supreme Court will dramatically alter the nation’s congressional elections under a highly disputed election law theory.

After roughly three hours of arguments Wednesday, the court’s three liberal justices—Sonia Sotomayor, Elena Kagan and Ketanji Brown Jackson—were skeptical of the so-called independent state legislature theory that gives state legislatures exclusive authority, with no judicial review, over rules for congressional elections and redistricting, subject only to intervention by Congress.