Whether, under a provision of the Clean Air Act, 42 U.S.C. § 7607(b)(1), the inclusion of a state regulation in an EPA-approved State Implementation Plan ("SIP") deprives state courts of their presumptive sovereign jurisdiction to determine whether the regulation is inconsistent with state law, where (a) 42 U.S.C. §7607(b)(1) does not unambiguously withdraw jurisdiction from state courts and (b) depriving state courts of their jurisdiction to determine whether a state regulation is inconsistent with state law would make the regulation effectively immune to facial state law challenges?

Whether state courts are deprived of jurisdiction to determine if a state regulation included in an EPA-approved State Implementation Plan is inconsistent with state law