In Pacific Merchant Shipping Ass'n v. Goldstene, the Ninth Circuit Court of Appeals affirmed a district court decision prohibiting the State of California from enforcing limits on diesel particulate matter, nitrogen oxide, and sulfur oxide emissions originating from diesel engines aboard marine vessels (the “Marine Vessel Rules”). Analyzing the case, Alyssa Moir writes: 

     Pacific Merchant, which involves California’s regulation of marine vessel emissions, represents the states’ most recent efforts to reduce emissions in California from mobile sources, specifically focusing on pollutants from the auxiliary diesel engines aboard marine vessels. In this case, the state simply tried to characterize required emissions reductions as something else — as “in use” requirements — and argued that no waiver was required. Neither the district court not the Ninth Circuit, however, bought the argument.

     California developed the Marine Vessel Rules as part of a broader plan intended to reduce air pollution from international trade and goods movement in the state. The Rules aimed to reduce diesel particulate matter (“diesel PM”), nitrogen oxides (NOx), and sulfur oxides (SOx) emitted by auxiliary diesel engines and diesel-electric engines on ocean-going vessels within 24 miles of California’s shoreline. The Rules limit emissions from auxiliary diesel engines to the emissions that would have occurred if the engine had been using an approved low-sulfur fuel. Alternatively, vessel owners could use emission control strategies, as opposed to particular fuels, to meet the same standard. Examples of emission control strategies include use of shore-side power, diesel oxidation catalysts, or diesel particulate filters. The Marine Vessel Rules exempted vessels traveling through waters within 24 miles of the California coastline but not entering or stopping at port, as well as vessels owned or operated by a local, state, federal or foreign government.

     . . . .

     In contrast to federal preemption of emissions standards, the [Clean Air Act] reserves to the states “the right … to control, regulate, or restrict the use, operation, or movement” of motor vehicles. Examples of these so-called “in-use requirements” include carpool lanes, restrictions on car use in downtown areas, and programs to control the idling of vehicles.” EPA interprets the [Clean Air Act] to extend in-use requirement regulations to nonroad engines. The California Air Resources Board … argued that the Marine Vessel Rules were “in-use requirements” rather than “emission requirements,” and therefore, that it did not need a § 209(e)(2) waiver from EPA. It began enforcing the Marine Vessel Rules shortly after they were enacted, beginning January, 2007.

(Footnotes omitted.)