Order unanimously affirmed, with costs. Memorandum: Service Employees International Union by instituting an action for injunctive *971relief did not waive its right under the union contract to demand arbitration to redress alleged past contract violations and to seek back pay for its members (see Preiss/Breismeister Architects v Westin Hotel Co.-Plaza Hotel Div., 56 NY2d 787, 789). (Appeal from order of Supreme Court, Erie County, Gossell, J. — stay arbitration.) Present — Hancock, Jr., J. P., Doerr, Denman, Moule and Schnepp, JJ.