California Code, Labor Code - LAB § 1128

(a) Where a party to a collective bargaining agreement prevails in a court action to compel arbitration of disputes concerning the collective bargaining agreement, the court shall award attorney's fees to the prevailing party unless the other party has raised substantial and credible issues involving complex or significant questions of law or fact regarding whether or not the dispute is arbitrable under the agreement.

If the dispute is later found to be not arbitrable under the collective bargaining agreement, any award made pursuant to this subdivision shall be vacated and those sums paid to satisfy the award shall be reimbursed to the payor.

(b) Where a party to a collective bargaining agreement appeals the decision of an arbitrator regarding disputes concerning the collective bargaining agreement, the court shall award attorney's fees to the prevailing appellee unless the appellant has raised substantial issues involving complex or significant questions of law.

(c) Where a party to a collective bargaining agreement prevails in a court action to compel compliance with the decision or award of an arbitrator or a grievance panel regarding disputes concerning the collective bargaining agreement, the court shall award attorney's fees to the prevailing party unless the other party has raised substantial issues involving complex or significant questions of law.

(d) This section shall not apply to public employment.