Under the Clean Air Act, the EPA was required to make a final decision (either to revise the NAAQSs or retain the old ones) no later than December 31, 1990. The EPA had not done so, and Sixty-seven electric utilities and three electric utility industry associations filed suit in the Eastern District of New York, alleging that it had breached its non-discretionary, statutory duty of reviewing (and if necessary revising), at five-year intervals, the NAAQSs for ozone. Ps sought an order to compel EPA to perform its statutory duties. The utilities moved to intervene as parties defendant. Their proposed answer asserted two defenses: (1) that 'the complaint fails to state a claim against Defendants upon which relief can be granted,” and (2) that the district court 'lacks subject matter jurisdiction over the Plaintiffs' complaint.' The trial judge ordered EPA, to publish a proposed decision, made pursuant to notice and comment rulemaking procedures, to revise (or not) the existing NAAQSs for ozone. The trial judge held that the utilities' interest in the subject matter of the action was based on a 'double contingency' of events: 'first, the plaintiffs must prevail in this lawsuit and second, the defendants must then downwardly revise the NAAQSs.” Thus, the utilities' interests were too 'remote from the subject matter of the proceeding' and too 'contingent upon the occurrence of a series of events.' In addition, because the utilities could participate in any rulemaking ordered by the court, a judgment in favor of the plaintiffs could not as a practical matter impair the utilities, ability to challenge any defect of any subsequent rulemaking. Further, c the utilities could not demonstrate an interest in the rulemaking schedule that would not be adequately represented by EPA. This appeal resulted.