The US Supreme Court issued a ruling in Rent-A-Center West v. Jackson.  The Supremes have found that an arbitrator should resolve issues regarding the enforceability of an arbitration agreement, and not the courts.  See decision.  This is an unfortunate decision.  Simply based on policy grounds, arbitrators earn income by hearing arbitrations.  So, they have

 Mandatory arbitration holds few benefits for the employee.  In the labor union context, it is helpful.  The union and employer can pick the arbitrator they want.  Both union and employer have knowledge of the different arbitrators and their particular biases.  So, both sides can make an informed selection when they choose arbitrators.  But, that does

 Arbitration has been around forever for labor disputes.  Unions and their employers have long relied on arbitration as a relatively inexpensive way to resolve disputes.  In the labor context, the arbitration process is set up through a collective bargaining agreement.  The arbitrator is picked by both sides from a list of some 10 ore more names.