The validity or applicability of a rule may be determined in an action for declaratory judgment in the Washington Superior Court if it is alleged that the rule, or its threatened application, interferes with or impairs, or threatens to interfere with or impair, the legal rights or privileges of the plaintiff. The agency shall be made a party to the action. A declaratory judgment may be rendered whether or not the plaintiff has requested the agency to pass upon the validity or applicability of the rule in question. (Added 1967, No. 360 (Adj. Sess.), § 7, eff. July 1, 1969; amended 1973, No. 193 (Adj. Sess.), § 3.)