The Ninth Circuit Court of Appeals has ruled that the Clean Air Act (CAA) does not preempt pollution-control rules adopted in 2007 by the Monterey Bay Unified Air Pollution Control District (MBUAPCD), which required registration and annual fees for certain diesel-powered engines used in agricultural operations. Jensen Family Farms, Inc. v. MBUAPCD, No. 09-16790 (9th Cir. 5/27/11). The case involved three rules designed to bring the air district’s regulatory program in line with California Air Resource Board (CARB) requirements for stationary and portable engines larger than 50 brake horsepower. Plaintiffs argued that the air district violated its constitutional rights by setting standards that only EPA has authority to establish under CAA and that the rules violated state laws and plaintiffs’ right to due process.

  While the CAA preempts any regulation regarding emissions standards for mobile sources, it leaves regulation of stationary sources primarily to the states. The court found that, even though Section 209(e) of the CAA expressly prohibits states from setting emissions standards for non-road sources, implied preemption existed as to whether California could adopt “standards or other requirements relating to the control of emissions” without first seeking permission from EPA.

Utilizing traditional statutory construction principles, the court concluded that the disputed regulations dealing with registration and fees “are not preempted by section 209(e)” of CAA because they had “nothing to do with emissions standards or the control of emissions” and “are likely outside of the scope of state law that Congress intended to preempt.” The court also rejected the notion that the regulations are preempted simply because they “relate to” emissions control, commenting that under this misguided logic “every rule promulgated by the District relating to non-road engines and vehicles would be preempted by § 209(e).”

The third disputed regulation, which “unquestionably set[] emissions standards,” was not preempted because the CAA definition of a “non-road engine” is mutually exclusive to the regulation’s definition of a “stationary [compression ignition] (CI) engine.” The CAA would preempt any portion of the regulation setting emissions standards for non-road engines, but since the pollution control board’s third regulation did not apply to any non-road engines as the term is used in the CAA, the court concluded that it was also not preempted. In affirming the district court’s decision, the Ninth Circuit also rejected plaintiffs’ state preemption and substantive due process arguments.