The California Supreme Court decided that an employer cannot require an employee to go to arbitration instead of a "Berman" hearing before the Labor Commissioner. Rather, the employee must be permitted to go to the labor commissioner and then the arbitration agreement can be used for the "appeal" de novo.
This 4-3 decision involves lengthy discussions of preemption and unconscionability.
The majority, led by retiring Justice Moreno, finds that the waiver of the labor commissioner hearing deprives the employee of so many benefits that the arbitration agreement violates public policy. The U.S. Supreme Court may take a look at this one under the Federal Arbitration Act. Until then, though, employees get to see the Labor Commissioner, even if they have arbitration agreements.
The case is Sonic-Calabasas A, Inc. v. Moreno and the opinion is here.