In Rochester City School Dist. v. Rochester Teachers Assn., 41 NY2d 578, 362 N.E.2d 977, 394 N.Y.S.2d 179 (1977), the Court of Appeals considered a substantially similar question.

There, the parties submitted a question of contract interpretation to an arbitrator.

Following the arbitrator's ruling, the Rochester City School District appealed, claiming that the arbitrator's decision was contrary to the unambiguous language of the contract, and that the arbitrator therefore "exceeded his power" by ruling as he did.

The Court of Appeals rejected this argument, holding:

A party who has participated in arbitration cannot later seek to vacate the award on the ground that the controversy was not arbitrable. By statute that question must be raised before arbitration, and if is not it is deemed to be waived. Obviously a party may not avoid this restriction by later arguing that the award should be vacated on the ground that the arbitrator exceeded his power' by construing the agreement when it was clear on its face and required no interpretation. (Id. at 583.)