IN THE Supreme Court of the United States OCTOBER TERM, 1972 No. 72-804 WILLIAM D. RUCKELSHAUS, Administrator of the V. SIERRA CLUB, ET AL. Petitioner, On Petition for a Writ of Certiorari to the United States Court of Appeals for the District of Columbia Circuit BRIEF FOR RESPONDENTS IN OPPOSITION OPINIONS BELOW The opinion of the district court (Pet. App. B, pp. 3a11a) is reported at 344 F. Supp. 253. The court of appeals affirmed on the basis of the district court's opinion (Pet. App. A, pp. 1a-2a). JURISDICTION The judgment of the court of appeals (Pet. App. A, pp. 1a-2a) was entered on November 1, 1972. The petition for a writ of certiorari was filed on December 4, 1972. The jurisdiction of this Court is invoked under QUESTION PRESENTED Whether the Clean Air Act of 1970 allows the Administrator of the Environmental Protection Agency to approve state-implementation fans which permit the significant deterioration of air quality in areas where existing air quality is better than the secondary ambient air quality standards. STATUTES INVOLVED Section 101 (b) of the Clean Air Act, 42 U.S.C. 1857 (b) (1) provides: The purposes of this subchapter are (1) to protect and enhance the quality of the Nation's air sources as to promote the public health and welfare and the productive capacity of its population Other provisions of the Clean Air Act of 1970, 42 U.S.C. 1857, et seq. are set forth in Appendix D to the petition, pp. 14a-22a. STATEMENT The Clean Air Act of 1970 requires the Administrator to establish national primary and secondary ambient airquality standards. 42 U.S.C. 1857c-4 (a) (1). Primary air-quality standards are the levels of air quality "requisite to protect the public health." 42 U.S.C. 1857c-4 (b) (1) (A). Secondary standards are the levels of air quality "requisite to protect the public welfare from any known or anticipated adverse effects associated with the presence of such air pollutant in the ambient air." 42 U.S.C. 1857c-4 (b) (2). The Clean Air Act requires as the mechanism for meeting the primary and secondary standards that each state submit a state-implementation plan to the Administrator of EPA. This plan must provide for "implementation, maintenance, and enforcement" of the primary and secondary standards. 42 U.S.C. 1857c-5 (a) (1). If the Administrator disapproved any state plan because it failed to carry out the requirements of the Act, he was required to promulgate his own regulations to replace the disapproved portion of the state plan. 42 U.S.C. 1857c-5 (c). The National Primary and Secondary Ambient Air Quality Standards adopted by the Administrator provide (40 C.F.R. 50.2 (c)): The promulgation of national primary and secondary air quality standards shall not be considered in any manner to allow significant deterioration of existing air quality in any portion of any State. Thus, these regulations, which are still in force, explicitly prohibit the significant deterioration of air quality which is better than secondary standards. Nevertheless, directly inconsistent with his regulation, the Administrator subsequently adopted Requirements for Preparation, Adoption, and Submittal of Implementation Plans which provide (40 C.F.R. 51.12 (b)): In any region where measured or estimated ambient levels of a pollutant are below the levels specified by an applicable secondary standard, the state implementation plan shall set forth a control strategy which shall be adequate to prevent such ambient pollution levels from exceeding such secondary standard. This provision would allow air quality better than secondary standards to deteriorate to the level of those standards. Respondents brought this action on May 24, 1972, in the United States District Court for the District of Columbia, challenging the validity of 40 C.F.R. 51.12 (b), supra, under the Clean Air Act. On May 30, 1970, the district court issued a preliminary injunction which the parties have subsequently stipulated should be treated as |