Prior to the Taft-Hartley Act of 1947, the enforcement of collective bargaining agreements was a matter for state courts, and they applied state law. In many states agreements to arbitrate could not be enforced at all. In some states an employer's refusal to honor an arbitration agreement resulted in an award of money damages, but the union still could not force the employer to actually engage in arbitration. In 1947, the Taft-Hartley Act gave unions the right to sue in federal court to enforce their collective agreements. Interpretation of collective agreements is a matter of federal law.
Arbitration clauses are enforceable.
The remedy for refusing to arbitrate is a court order to engage in arbitration. An employer must arbitrate all disputes, including frivolous ones. A court cannot reject an arbitrator's findings of fact simply because it disagrees with them. Although the NLRB does not enforce arbitration agreements or enforce arbitrators' awards, the Board routinely allows the arbitration process to substitute for its own administrative processes in unfair labor practice cases. If a union files an unfair labor practice charge against an employer, and there is a collective agreement containing an arbitration clause, then the Board usually will decline to exercise jurisdiction and await the outcome of the arbitration.