In 2013, the trucking and road construction industries initiated a case to prevent the EPA from waiving federal emissions standards for nonroad diesel engines to allow the California Air Resources Board (CARB) to impose its own more stringent standards on those vehicles. The outcome of that dispute will carry major consequences for California businesses and, possibly, businesses in other states that chose to adopt the California standards. But the case has not yet been heard because the parties are in disagreement over which of two courts has jurisdiction—the U.S. Court of Appeals for the D.C. Circuit or the U.S. Court of Appeals for the 9th Circuit. On December 18, 2015, the D.C. Circuit sided with the industry petitioners by ruling that the case is a state matter and therefore must be heard by the 9th Circuit.
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The Clean Air Act (CAA) authorizes the EPA to issue national emissions standards for vehicles. However, the CAA also gives special consideration to California, which may issue its own vehicle emissions standards once the EPA has waived the federal standards and provided California’s standards are at least as stringent as the federal standards. The state has been granted many such waivers over the decades. Also, once California finalizes its vehicle emissions standards, any other state may adopt them.