DOJ Ends Criminal Crackdown on Diesel Emissions System Removal

The Department of Justice has ended its criminal crackdown on mechanics and garage owners who remove emissions control systems from diesel trucks.

The decision marks a major U.S. policy shift, halting a yearslong federal effort to prosecute the sale and installation of illegal “defeat devices” used to boost vehicle performance, The New York Times reports.

In an announcement shared on X earlier this year, the Justice Department stated it was “exercising its enforcement discretion” to stop pursuing criminal charges. The post, which received minimal attention outside the automotive sector, stated that the department was “committed to sound enforcement principles, efficient use of government resources, and avoiding over-criminalization of federal environmental law.”

Though federal authorities stated they would continue to pursue civil lawsuits and financial penalties, the sudden policy shift has immediately affected ongoing criminal cases across the country, prompting prosecutors to drop active charges.

The change aligns with broader efforts by the Trump administration to scale back clean-air regulations, which officials argue place an unnecessary financial burden on businesses.

The decision effectively ends an enforcement campaign that federal agencies previously described as vital for public health. According to an Environmental Protection Agency report from 2020, more than 550,000 diesel pickup trucks had their emissions controls removed between 2010 and 2020. That figure accounts for roughly 15 percent of all certified diesel trucks nationwide.

The EPA calculated that removing these systems allows trucks to emit nitrogen oxides at up to 300 times the legal limit.

To illustrate the scale of the pollution, the agency determined that the excess emissions from those 550,000 modified trucks had the same environmental impact as adding more than nine million standard, unmodified diesel pickups to American roads. Nitrogen oxides contribute significantly to smog and respiratory illnesses, while diesel exhaust also releases fine particulate matter that can damage lungs and enter the bloodstream.

Federal interest in these workarounds intensified following the 2015 Volkswagen scandal, in which the automaker was caught using secret software to cheat laboratory emissions tests.

After that case, federal prosecutors began targeting smaller independent shops that sold hardware and software kits allowing everyday truck owners to “delete” their factory emissions systems. These modifications became popular because factory pollution-control systems can strain engines, lower fuel efficiency and trigger a vehicle’s computer to enter an inoperable “limp mode” when a component fails.

The abrupt end to criminal enforcement has drawn criticism from former prosecutors.

Vanessa Waldref, a former U.S. attorney for the Eastern District of Washington who oversaw several defeat device investigations, told The New York Times that the policy shift was frustrating. Waldref, now a partner at the firm Singleton Schreiber, emphasized that her team was confident in the legal framework of their investigations.

“Criminal enforcement is a critically important tool for really sending an important message of accountability, and what our community standards should be for protecting public health and the environment,” Waldref said, adding that relying solely on civil fines risks turning penalties into “just the cost of doing business.”

Conversely, defense attorneys and defendants argue that the criminal charges were an overreach.

Stewart Cables, an attorney based in Boulder, Colorado, who represents people accused of installing these devices, told the publication that defense lawyers had long maintained that the Clean Air Act only authorizes civil lawsuits, not felony charges, for vehicle emissions tampering. Cables argued that criminal liability should apply only to stationary pollution sources like factories.

“We believe that the Trump administration got it right when they eliminated the criminal liability for this conduct,” Cables said. “If you want to make tampering with a mobile source a felony, go to Congress.”

The policy shift has left previous defendants facing permanent criminal records.

Mackenzie Spurlock, the 31-year-old owner of Matanuska Diesel in Wasilla, Alaska, pleaded guilty last year after a 2022 EPA raid revealed he had been paid to remove emissions controls from at least 20 vehicles. Spurlock received probation and a $32,000 fine, and his felony status now prevents him from rejoining the National Guard.

Spurlock told The New York Times that factory emissions systems frequently fail during freezing Alaskan winters, leaving motorists stranded.

“Nobody wants to hurt the environment,” Spurlock said. “It isn’t about trying to break the law. People want reliability.”