In Opalinski v. Robert Half International Inc., 761 F.3d 326 (3d Cir. 2014) (No. 12-4444), the Third Circuit determined that a court, rather than an arbitrator, should decide if an agreement to arbitrate authorizes classwide arbitration because it is a “gateway” question of arbitrability. The court concluded that absent clear evidence otherwise, such as a clause delegating that decision to the arbitrator, the availability of classwide arbitration is a “gateway” or substantive question of arbitrability, and as such, is to be decided by a court. The court noted that gateway issues of arbitrability are for the court is to decide, while procedural questions about the arbitration are for the arbitrator to decide. Gateway issues include whether the parties are bound by an arbitration clause or whether an arbitration clause in a binding contract applies to a particular type of controversy. Here, the court concluded that the differences between individual arbitration and class arbitration are so great that a choice between the two implicates the very type of controversy to be resolved. As a result, the availability of classwide arbitration is a gateway issue for the court. This presumption may only be overcome by proof that the parties “clearly and unmistakably” provided otherwise, such as by contractual language unambiguously delegating the question of arbitrability to the arbitrator.