EDF, NRDC, Sierra Club join court fight in support of California clean truck measures

Environmental Defense Fund (EDF), Natural Resources Defense Council (NRDC), and Sierra Club are helping defend California’s protective clean vehicle standards in court. 

Last year, truck manufacturer filed a court challenge to California’s standards limiting the emission of harmful air pollutants, as well as to California's Clean Truck Partnership – a voluntary agreement signed in 2023 between the California Air Resources Board (CARB) and major truck manufacturers that represent more than 90% of the state’s truck market.

On Tuesday, EDF, NRDC and Sierra Club filed an amicus brief (or "friend of the court" brief) in the U.S. District Court for the Eastern District of California in support of the California’s clean truck measures.

“The state measures Plaintiffs seek to enjoin address some of the most virulent and deadly forms of air pollution. Emissions from the diesel-powered heavy-duty motor vehicles cause enormous harm to millions of Californians, and account for an outsized share of California’s chronic air quality problems,” the groups state in their brief. “Disabling the California regulations means more air pollution and shortened lives for Californians.”

The transportation sector is an enormous source of climate and health-harming pollution in California, including deadly particle pollution, smog-forming nitrogen oxides (NOx) and other dangerous air pollutants. Particulate pollution from the diesel engines used in most heavy-duty vehicles poses particularly severe health risks.

California began regulating vehicle pollution long before the federal government did and has been a leader in creating policies and technologies to limit it and protect Californians’ health. California also has specific geographic and other challenges that cause especially significant air pollution problems. Under the Clean Air Act, Congress specifically granted California the right to set its own air pollution standards with waivers from the Environmental Protection Agency. EPA has granted dozens of these waivers over more than half a century.

EDF analysis finds California’s more than 50 years of emission standards have significantly reduced harmful emissions, leading to substantial improvements in air quality, protecting thousands of lives, and saving billions of dollars. One program alone, which is now under attack in this lawsuit – the Omnibus Low NOx regulation – is expected to reduce pollution by 2050 in amounts that will result in as many as 4,800 fewer Californians dying prematurely, along with fewer hospitalizations and ER visits.

Last year, Congress used the Congressional Review Act in an attempt to reverse three already-approved waivers for California’s vehicle standards – in spite of the fact that the Congressional Review Act’s plain language does not cover agency adjudications such as preemption waivers and only authorizes Congress to disapprove federal laws. The Senate Parliamentarian, the office specially charged with determining which agency actions are subject to Congressional review, the independent Congressional Research Service, and even long-time Congressional opponents of California’s actions consistently agreed that waivers for California’s state vehicle standards are not subject to the Congressional Review Act. 

California and 10 other states also filed a lawsuit in the United States District Court for the Northern District of California. EDF and partners filed an amicus brief in support of California in that case in January 2026. That case is pending.