Trump Administration Sues California to Void Its Vehicle-Emission and Zero-Emission Rules

On March 12, 2026, the Trump administration filed suit against California air regulators seeking to invalidate the state's vehicle greenhouse-gas and zero-emission vehicle requirements, arguing the state lacks authority to enforce any of its vehicle emission regulations. Transportation Secretary Sean Duffy described the state's requirements as an illegal EV mandate. California's standards, adopted under a Clean Air Act waiver framework that other states may follow, have historically set the effective national floor for vehicle emissions.

The suit asks a court to strip a regulatory authority Congress created by statute and that federal agencies have administered through waivers for decades, rather than to withdraw a waiver through the administrative process. The outcome determines whether states retain any independent role in vehicle pollution regulation.

The case was pending as filed. California officials have said they will defend the rules.