proper definition of the appropriate roles of arbitrators, administrative agencies and the courts depends in great part on the notion that, generally speaking, in labor relations, the interpretation and application of contracts is for arbitrators, and the interpretation and application of statutes is for the administrative agencies and the courts. Arbitrators deal primarily with contract rights and administrative agencies, like the NLRB and the courts, deal primarily with statutory rights. If that distinction is maintained, the problems of deferral to arbitration and the use of external law in arbitration can be more easily resolved.
St. Antoine, Theodore J. "Deferral to Arbitration and Use of External Law in Arbitration." Indus. Rel. L. J. 10 (1988): 19-26.