Senate bill would strip California's authority to enforce tighter truck emission rules

What does this do?

SJRES 47 uses the Congressional Review Act to cancel an EPA waiver granted in January 2025 that allowed California to enforce its own stricter nitrogen oxide (NOx) emission rules for heavy-duty trucks and diesel engines. Without the waiver, California's "Omnibus Low NOx" regulation would become unenforceable. Other states that had adopted California's stricter standards in place of the federal standard would also likely be affected.

Who does it affect?

Trucking companies, diesel engine manufacturers, and freight operators doing business in California and any states following California's emission rules are most directly affected. California residents and residents of other adopting states who would otherwise have seen air quality improvements are also affected.

Why does it matter?

NOx pollution contributes to smog and respiratory health problems, and the stricter standards were designed to reduce those effects. Revoking the waiver removes the legal basis for enforcing those reductions in California and likely in states that follow its rules. Engine requirements tied to cleaner standards can also influence the cost and availability of heavy-duty trucks and the goods they transport.

Where does it stand?