On June 2, the U.S. Court of Appeals for the D.C. Circuit categorically rejected consolidated petitions by several states, municipalities, industrial entities, and environmental groups challenging findings by the Environmental Protection Agency that designated regions had failed to meet certain ozone restrictions under the Clean Air Act (42 U.S.C. §§ 7401 et seq.). 

At issue was Title I of the Act, which requires the EPA to promulgate National Ambient Air Quality Standards (“NAAQS”), thereby establishing the maximum level of permissible pollutant concentration in the atmosphere.  The EPA must then discern whether states – and, particularly, geographical areas within such states – are in “attainment” with these ground-level ozone NAAQS.  Although the petitioners here employed various arguments against the EPA’s findings, nearly every entity claimed that the agency acted arbitrarily and capriciously in rendering these NAAQS designations. 

For instance, Delaware and Connecticut had complained that they could never obtain “attainment” status because activity from other states like Illinois and Indiana damages their air quality. 

In an 87-page opinion, a D.C. Circuit panel rejected these petitions in their entirety.  The court found that the EPA “complied with the Constitution, reasonably interpreted the Act’s critical terms and wholly satisfied – indeed, in most instances, surpassed – its obligation to engage in reasoned decision-making.” 

The case is Mississippi Commission on Environmental Quality et al. v. U.S. Environmental Protection Agency et al., case number 12-1309, in the U.S. Court of Appeals for the District of Columbia Circuit.