Despite Congressional directive and courtroom losses, Illinois is not giving up on adopting California’s strict vehicle emission standards.

California’s vehicle emission rules have been the center of controversy since they were proposed. For truck drivers, Advanced Clean Fleets, Advanced Clean Trucks, and the Omnibus Low NOx regulation would have significantly increased the cost of a new truck.

Per the Clean Air Act, no state may implement vehicle emission rules stricter than federal regulations. However, an exception is carved out for California to address its out-of-control air pollution problem. Before enforcing new emission rules, California must obtain a waiver from the U.S. Environmental Protection Agency. Once that waiver is obtained, any state can adopt California’s standards.

Ten states adopted Advanced Clean Trucks, nearly all of which also adopted the Omnibus rule. Only a few chose to start implementing those rules for model year 2025 trucks after several states pushed back the start date. More than a dozen states adopted Advanced Clean Cars II, emission rules for passenger vehicles. Two states – Illinois and Maine – have a rulemaking process to adopt California’s vehicle emission rules.

California’s vehicle emission rules were shot down last June. Congress passed resolutions to revoke EPA waivers for Advanced Clean Trucks, Advanced Clean Cars II and the Omnibus rule. That effectively stopped California and adopting states from enforcing the stricter emission rules.

Those states are currently challenging those resolutions in the courtroom. A ruling on a motion to dismiss that lawsuit is pending.

Until a court ruling states otherwise, California’s stricter vehicle emission rules are dead. However, Illinois is still standing by for a favorable ruling.

Doubling down on vehicle emission rules

Illinois’ battle to implement stricter vehicle emission rules has been a losing one so far.

In 2023, the state attempted to adopt California’s vehicle emission rules legislatively. Only eight lawmakers signed. More than 90% of submitted witness slips opposed the bill. It died in committee.

Garnering no support from lawmakers or the public, Illinois took a second bite at the apple through the regulatory process. Rather than codify vehicle emission rules into law, as other states have done, Illinois decided to adopt California’s rules as regulations. In 2024, the state Pollution Control Board started the rulemaking process.

Illinois’ vehicle emission rulemaking process was put on hold after Congress invalidated the rules the state wanted to adopt. Despite the setback, Illinois is still clinging onto some hope.

On March 5, the rule’s proponents informed the Pollution Control Board that they are staying the course. The status report keeps the proposed rule alive for at least another six months.

Proponents pointed to the EPA’s move in February to officially withdraw the 2009 endangerment finding. All vehicle emission rules based on greenhouse gases hinged on that one document. The rule proponents said “the Trump administration’s aggressive deregulatory actions have raised the stakes of this rulemaking proceeding and highlighted the importance of state action to protect local air quality and combat climate change.”

“Due to these rollbacks, the benefits of adopting the Illinois Clean Car and Truck Standards proposed here would be far larger than Rule Proponents projected in 2024 because those benefits were calculated against a baseline of federal standards in effect at that time,” the status report states.

Without a court ruling Congress’ resolutions are unlawful, Illinois will have no path to finalize and enforce its proposed vehicle emission rules.

California truck emission rules in limbo

Advanced Clean Trucks and the Omnibus rule are not the only truck emission rules under attack in California.

California’s Clean Truck Check has required all trucks operating in the state to pass an emission test. That included trucks registered outside the state. Essentially, all trucks with a 2009 or older engine were banned.

In January, the EPA issued a final rule disapproving of the requirement on out-of-state trucks. Effectively, emissions tests apply only to trucks registered in California, allowing any out-of-state truck to enter.

That should be the end of it, but the California Air Resources Board is digging in its heels. CARB told Land Line that it will continue to apply Clean Truck Check to out-of-state trucks, regardless what the EPA has decided.

“This announcement is a whole lot of bluster about bean counting,” a CARB spokesperson said in a statement. “EPA has no authority over this program and we will continue to enforce the law to ensure that all trucks coming into and operating in California abide by the same rules — even if EPA doesn’t want to give us credit.”

Can older, out-of-state trucks operate in California without an emissions inspection test? As of March 11, the answer is “No.”

EPA’s disapproval prevents California from using those emissions inspections toward its federal emissions-reduction targets. As long as the state meets those targets in other ways, it can continue to require Clean Truck Checks on out-of-state trucks and impose fines for noncompliance.

As for Advanced Clean Trucks and the Omnibus rule, those regulations are completely unenforceable. A legal challenge is pending, but Congress’ resolutions remain in effect while litigation is pending. LL