The interests of employers and independent contractors in the transportation industry clashed Wednesday in the U.S. Supreme Court as the justices wrestled with whether those workers must submit their disputes to arbitration.

The major issue in New Prime v. Oliveira centers on an arbitration exemption in Section 1 of the Federal Arbitration Act. The exemption applies to “contracts of employment of seamen, railroad employees, or any other class of workers engaged in foreign or interstate commerce.”