It was one of the easiest ways to make a diesel truck faster, more powerful and more reliable: Pay a local shop to quietly gut the emissions controls with an illegal “defeat device.”
Now the federal government has largely stopped prosecuting the people who sell and install them.
The devices, which often include both hardware and software, began exploding in popularity about 20 years ago as pollution-control systems made tailpipe emissions cleaner but put more strain on engines. Some truck owners and mechanics have called defeat devices a necessity.
By 2020, the most recent numbers available, the E.P.A. estimated that the emissions controls had been removed from more than 550,000 diesel pickup trucks over the prior decade, or roughly 15 percent of all diesel trucks originally certified with those controls. The effect, the agency found, was the equivalent of adding more than nine million additional diesel pickups to American roads, spewing harmful nitrogen oxides at levels up to 300 times the legal limits.
After a headline-grabbing case in 2015 in which Volkswagen was caught secretly using defeat-device software in millions of its cars, the Justice Department began to pursue criminal charges under the Clean Air Act against shop owners who installed the devices on individual vehicles. Those prosecutions have now ended, according to a Justice Department post on X earlier this year that went little-noticed outside the trucking world.
The policy change is in keeping with the Trump administration’s sweeping rollbacks of clean-air regulations that it argues are expensive and onerous. The White House and the E.P.A. have taken aim at greenhouse gas rules and pushed to end Biden-era efforts to encourage electric vehicles instead of those burning planet-warming fossil fuels. The agency has also targeted California’s stricter auto-emissions rules and sought to delay tailpipe standards that were scheduled to take effect next year.
In the post on X, the department said that it was “exercising its enforcement discretion” to no longer pursue criminal charges. It said it was “committed to sound enforcement principles, efficient use of government resources, and avoiding over-criminalization of federal environmental law.”
The Justice Department said at the time that it would still pursue civil enforcement — suing companies or individuals — for violations. The department declined to comment for this article.
Because the change was based on prosecutorial discretion, the policy could be reversed under a different administration.
The new policy has had an immediate effect on open cases across the country, as prosecutors moved to drop charges that could have resulted in years in prison. It stung particularly hard for defendants whose cases had already been closed, some of whom are now seeking presidential pardons or trying to recoup their legal fees.
Mackenzie Spurlock, 31, owns Matanuska Diesel, a small shop in Wasilla, Alaska, that was raided by investigators from the Environmental Protection Agency in 2022. He was charged with collecting at least $30,000 for removing emissions controls from at least 20 vehicles.
He pleaded guilty last year, which means he is now a felon, a designation that among other things prevents him from rejoining the National Guard, where he spent six years as an aircraft mechanic. “After going through this experience, it makes you realize how weaponized the government was at that point,” Mr. Spurlock said. He was put on probation and fined $32,000.
Mr. Spurlock argued that modern emissions control systems often rendered trucks inoperable in Alaska’s harsh winters, leaving drivers stranded in subzero temperatures. He said he was simply trying to help his customers.
Emissions-control systems involve equipment in tailpipes, connected to a vehicle’s computer, that uses a combination of methods to trap and neutralize pollution. But they can also reduce an engine’s power and fuel efficiency. And if a vehicle’s computer system detects that the emissions controls are failing, it can put the truck into “limp mode,” rendering it inoperable until repairs are made.
“Nobody wants to hurt the environment,” Mr. Spurlock said. “It isn’t about trying to break the law. People want reliability.”
The E.P.A. has taken steps to address automatic engine shutdowns related to onboard diagnostics systems that affect truckers and farmers who rely on diesel vehicles. The agency referred questions about the criminal policy shift to the Justice Department.
Stewart Cables, a lawyer in Boulder, Colo., who specializes in defeat-device cases, said that he and other defense lawyers had long argued that the Clean Air Act authorizes only lawsuits, not criminal cases, over vehicle emissions. In fact, that had been the government’s practice until 2018.
“It was always our argument that, ‘OK, this is illegal, but it’s a civil violation,’” Mr. Cables said. “And then they start charging the felonies, which is where everything got all backward.” Mr. Cables is trying to obtain a pardon for Mr. Spurlock in light of the Justice Department’s new policy on criminal prosecutions.
According to Elizabeth Loeb, who was a lawyer at the Justice Department who worked on defeat-device cases during the first Trump administration, defeat devices had become readily available by around 2016. The kits, often including hardware and software, could be found easily online at the time.
“You could search ‘delete pipes’ on Amazon or eBay and hundreds of them would come up,” Ms. Loeb said.
The Justice Department sued eBay in 2023 over the fact that defeat devices, as well as other potentially harmful products, were for sale there. A judge dismissed the case, saying eBay couldn’t be held liable for its users’ products. Amazon said it now prohibits the sale of devices that may interfere with an engine’s emissions control system.
Federal officials had gained expertise in defeat devices during the sprawling 2015 case against Volkswagen. VW had sold cars that could detect when they were undergoing emissions testing in a lab and temporarily turn on pollution controls during the test. But when the cars were on the road, the pollution controls would shut off, causing the vehicles to emit levels of nitrogen oxides far above legal limits.
Volkswagen ultimately paid more than $30 billion in fines and legal fees. Other automakers faced similar accusations. Mercedes-Benz, for example, agreed last year to pay up to $150 million in a settlement reached with nearly all American states over the devices, and denied any wrongdoing.
Amid that scandal, American prosecutors began looking at smaller operations that sold or installed defeat devices.
The pace of criminal charges accelerated dramatically during the Biden years. Prosecutors brought charges in a handful of cases before the 2021 inauguration, and about 40 during the Biden administration.
The E.P.A. put out an “enforcement alert” in 2020 warning shops that they could face charges for installing the devices and reminding them of the dire effects of air pollution. Nitrogen oxides create smog and contribute to respiratory illnesses. Diesel trucks also produce high levels of particulate matter, or soot, which can penetrate deep into the lungs and the bloodstream, as well as other pollutants like lead and mercury.
Vanessa Waldref, a former U.S. attorney for the Eastern District of Washington who oversaw several defeat device investigations, said the department’s about-face on criminal enforcement was frustrating. Her team was confident in the legal grounding of the cases, she said, and had spent significant time on the 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,” said Ms. Waldref, who is now a partner at the firm Singleton Schreiber focused on environmental matters and wildfires. She also disputed the Justice Department’s position that air-pollution cases involving vehicles shouldn’t include criminal charges. The loss of such a powerful tool weakens law enforcement officials’ hands, she said, because civil penalties like fines can “turn into just the cost of doing business.”
The position of lawyers like Mr. Cables, who defends people accused of installing or selling defeat devices, is that the Clean Air Act allows for criminal charges related to tampering with emissions controls only on stationary sources of pollution, like power plants or oil refineries. “We believe that the Trump administration got it right when they eliminated the criminal liability for this conduct,” Mr. Cables said. “If you want to make tampering with a mobile source a felony, go to Congress.”
