In an action by a commercial tenant, inter alia, to declare the tax escalation clause of a written lease to be unconscionable within the meaning of section 235-c of the Real Property Law, the appeal is from a judgment of the Supreme Court, Kings County, dated April 3, 1980, which, after a nonjury trial, was in favor of the defendant. Judgment affirmed, with costs. The referee properly determined that the instant action was barred by the doctrine of res judicata due to the judgment in a prior declaratory judgment action between the parties involving the interpretation of the same tax escalation clause (Whitman Owner Corp. v 75 Henry St. Garage, 56 AD2d 867, mot for lv to app den 42 NY2d 810). The enactment of section 235-c of the Real Property Law did not give rise to a new cause of action in favor of the plaintiff herein, but was merely designed to codify the common-law doctrine of unconscionability and make clear the availability of the defense in the landlord-tenant context (see 35 Park Ave. Corp. v Campagna, 48 NY2d 813). In any event, the clause in question is not unconscionable. As found by the referee, the lease was negotiated by the parties at arm’s length, with experienced counsel of their own choice, and the tax escalation clause was knowingly and intelligently arrived at by the parties and their lawyers, without any misrepresentations or withholding of the facts. Mollen, P. J., Hopkins, Mangano and Cohalan, JJ., concur.