(1) The validity or applicability of a rule may be determined in an action for declaratory judgment in the district 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 petitioner.
(2) The agency shall be made a party to the action.
(3) A declaratory judgment may be rendered whether or not the petitioner has requested the agency to pass upon the validity or applicability of the rule in question.