The Trump EPA and Congress have engaged in a concerted effort to rein in California’s attempts to expand the effects of its truck emissions regulations beyond California. On August 26, EPA published a notice in the Federal Register proposing to deny approval of California’s application to include in its State Implementation Plan (“SIP”) the Heavy-Duty Inspection and Maintenance Regulation (“HD/IM”) (also referred to as the Clean Truck Check (“CTC”) regulation) as it applies to trucks registered outside of California. The California Air Resources Board’s (“CARB”) CTC regulation generally requires trucks over 14,000 pounds to register with CARB, pay an annual fee per vehicle, and submit to testing twice per year to demonstrate that the truck emissions control systems are functioning properly. By applying the regulation to trucks based outside of California but occasionally travel into California, EPA argues California is violating the Commerce Clause of the U.S. Constitution and therefore, California cannot provide assurances that its SIP, if approved, would be consistent with federal law as required under the federal Clean Air Act.

Under the Clean Air Act, EPA sets ambient air quality standards for certain pollutants and states must submit SIPs (or SIP revisions) to maintain and enforce those standards. EPA reviews SIPs and, if approved, the state regulations included in a SIP become enforceable as federal law. As EPA admits in its Federal Register notice, “The EPA acknowledges, however, that the extraterritorial reach of the State’s regulation is unusual in the SIP context and that the EPA’s response would necessarily be the first instance in which the Agency has disapproved a SIP on this basis.”

In a somewhat analogous situation, motor carriers may recall that EPA approved inclusion of CARB’s Truck and Bus Regulation (“TBR”) as part of California’s SIP in 2012. That regulation, which now generally requires trucks to have 2010 model year engines or newer, has been enforced against trucks that are based out-of-state but enter into California. The Owner-Operator Independent Drivers Association (“OOIDA”) challenged the TBR’s application to out-of-state trucks as violating the Commerce Clause, but the Ninth Circuit upheld dismissal of OOIDA’s challenge on jurisdictional grounds without getting to the merits of the Commerce Clause arguments.

Whether EPA’s disapproval with respect to the CTC would prohibit California from enforcing the CTC against out-of-state trucks is unclear. However, at minimum, it would provide a roadmap for arguing that such enforcement violates the Commerce Clause.