The Nickel Report

On June 18, 2025, the Supreme Court decided Oklahoma v. EPA and EPA v. Calumet, a pair of cases that focus on the Clean Air Act’s (CAA or Act) venue selection provisions.

The judicial review provisions of the Act send review of “nationally applicable” EPA actions to the DC Circuit and review of “locally or regionally applicable” EPA actions to the regional circuits. See 42 U.S.C. § 7607(b)(1). However, in an exception to that rule, venue may lie in the DC Circuit for regionally applicable actions that are “based on a determination of nationwide scope or effect.” In the Court’s two recent decisions, it explained that the CAA venue analysis called for a two-step inquiry. First, courts must decide whether the EPA action is nationally applicable or only locally or regionally applicable; if nationally applicable, the case belongs in the DC Circuit. Second, if locally or regionally applicable, courts must decide whether the case falls within the exception for “nationwide scope or effect” to override the default rule of regional circuit review.

Since President Trump’s inauguration and the beginning of Scott Pruitt’s tenure as administrator of the U.S. Environmental Protection Agency (EPA), much of the focus of Clean Air Act activity in the new administration has been on global climate change issues. As more time passes, however, EPA is beginning to address other areas of Clean Air Act regulatory policy, and, in some respects at least, charting a new course that departs from the record of the Obama administration. One of the areas to which EPA has started to give renewed attention is the regional haze program.

During much of the Obama administration, states and EPA were in conflict about how to craft Clean Air Act plans to reduce “regional haze” impairment of visibility in national parks and wilderness areas. The technical and policy issues are daunting. Regional haze forms in the atmosphere from many sources’ air emissions — emissions from cars and trucks, construction equipment, factories and power plants (among others), plus natural sources like wildfires and dust storms. Developing regional haze implementation plans entails complex policy choices and weighing sometimes heavy compliance costs for emission controls — costs that may total in the hundreds of millions or even billions of dollars — against improvements in visibility that can be hard to measure and in some cases are even imperceptible to the human eye.