On July 3, 2026, President Trump announced full pardons for nine individuals convicted under the Clean Air Act for selling and installing “defeat devices” — aftermarket equipment that reprograms diesel trucks to bypass federally required emissions controls. The pardoned include Ryan and Wade Lalone from Gaylord, Michigan; Tim Clancy; Joshua Davis; Barry Pierce; Aaron Rudolf; Jonathan Achtemeier; and MacKenzie “Mac” Spurlock, an Alaska-based mechanic. Trump characterized their prosecutions as persecution by the Biden Administration, describing the work as simply “fixing their car.” The pardons are remarkable not for what they change legally, but for what they highlight about enforcement priorities. These men had been convicted of federal crimes for tampering with pollution-control systems on vehicles.
Some of their modifications affected dozens of vehicles; others touched hundreds of thousands. Yet despite the pardons, the Clean Air Act itself remains unchanged. The federal prohibition on emissions-control tampering remains law. Their vehicles, if driven on public roads, remain in violation of federal regulations unless those regulations are rewritten.
Table of Contents
- WHAT DID THESE DIESEL MODIFICATION ENTHUSIASTS DO TO WARRANT CONVICTIONS?
- THE SCALE OF EMISSIONS-CONTROL TAMPERING AND ITS ENVIRONMENTAL IMPACT
- THE DEFEAT DEVICES AT THE HEART OF THE CONVICTIONS
- WHAT HAPPENS TO MODIFIED VEHICLES AFTER THE PARDONS?
- WHY THE CLEAN AIR ACT STILL PROHIBITS THIS WORK
- THE TRUMP ADMINISTRATION’S APPROACH TO ENVIRONMENTAL REGULATION
- WHAT THIS MEANS FOR DIESEL MECHANICS AND ENTHUSIASTS
WHAT DID THESE DIESEL MODIFICATION ENTHUSIASTS DO TO WARRANT CONVICTIONS?
The individuals who received pardons were not hobbyists tinkering in home garages. They were commercial operators selling and installing defeat devices — specialized software and hardware modifications that reprogram diesel engines to disable or suppress their emissions-control systems and diagnostic warning systems. A defeat device can increase engine power and remove speed limiters, which is why the diesel enthusiast community prizes them. But that performance gain comes at a cost: these vehicles emit nitrogen oxides and particulates far in excess of federal limits. The scope of their operations varied widely.
Ryan and Wade Lalone, along with their business, modified numerous vehicles through their operation. Tim Clancy, Joshua Davis, Barry Pierce, Aaron Rudolf, Jonathan Achtemeier, and MacKenzie Spurlock were prosecuted for similar work. The scale ranged from dozens of vehicles to cases where hundreds of thousands of vehicles received modifications, depending on the individual’s position in the supply chain. Some were installers; others were suppliers of the defeat device software or hardware itself. The cumulative environmental footprint of these modifications is substantial — a single diesel truck with a defeat device can emit pollutants equivalent to dozens of compliant vehicles.
THE SCALE OF EMISSIONS-CONTROL TAMPERING AND ITS ENVIRONMENTAL IMPACT
Understanding why these cases were prosecuted at all requires understanding what defeat devices do to air quality. The federal emissions standards for diesel vehicles exist because diesel engines produce nitrogen oxides and particulate matter at levels that contribute to smog, respiratory disease, and premature death. Nitrogen oxides react with sunlight to form ground-level ozone, a known respiratory irritant. Particulates penetrate deep into the lungs and have been linked to cardiovascular and respiratory mortality. The Clean Air Act gives the Environmental Protection Agency authority to regulate vehicle emissions and to prosecute defeat device manufacturers and installers. The law treats defeat devices seriously because their impact scales rapidly. One truck with a defeat device is one problem; ten thousand trucks with defeat devices constitute a public health emergency.
Consider a real-world scenario: a tuning shop in a metropolitan area installs defeat devices on five hundred pickup trucks over five years. If each truck operates for ten years and travels twelve thousand miles annually, that’s a cumulative sixty million miles of high-emission driving that would not have occurred under federal compliance. The air pollution from that single shop’s work can affect thousands of people in the surrounding region. A critical limitation to recognize is that defeat device prosecutions have always been rare relative to the scale of the problem. The Federal trade Commission and EPA rely on complaints, tips, and targeted investigations to identify violators. Many defeat device installations likely go undetected. The convictions of these nine individuals may represent only a fraction of the defeat device trade operating in the United States.
THE DEFEAT DEVICES AT THE HEART OF THE CONVICTIONS
Defeat devices are not crude modifications. Modern defeat devices use sophisticated software to detect when a vehicle is undergoing an EPA emissions test (tests typically occur on dynamometers under controlled conditions) and to switch the engine into a compliant mode during testing, then revert to the high-emission mode during normal driving. This is why they earned the name “defeat device” — they are designed to defeat the emissions test itself. Some defeat devices flash new firmware directly onto the engine control unit.
Others use auxiliary devices that intercept sensor signals. The most common approach in the diesel enthusiast community is a software flash that removes speed limiters, disables the selective catalytic reduction system (which uses urea to convert nitrogen oxides into harmless nitrogen), or reprograms the diesel particulate filter to regenerate less frequently. Mechanics like MacKenzie Spurlock, working out of Alaska, would install these modifications in customer vehicles, often advertising improved performance and fuel economy. The performance gains are real — a modified diesel truck might see twenty to thirty percent more horsepower. But that power comes from burning more fuel less completely, generating more pollution in the process.
WHAT HAPPENS TO MODIFIED VEHICLES AFTER THE PARDONS?
A pardon ends criminal liability for the individuals. It does not alter the legal status of the vehicles they modified. Those trucks remain in violation of the Clean Air Act when operated on public roads in their modified state. The owners of those vehicles have not been pardoned. They face potential civil penalties, equipment violations under state emissions regulations, and the requirement to restore their vehicles to compliance or cease driving them on public roads. This creates a practical ambiguity.
Some modified vehicle owners might interpret the pardons as tacit permission to continue operating their trucks in modified form. State environmental agencies, however, are not bound by federal pardons. Many states have their own emissions regulations and inspection programs. California, for instance, operates an independent emissions-testing regime and can prohibit non-compliant vehicles from registration. A truck that is legal in one state under federal pardon might still fail to register in another state due to state-level environmental law. The pardon protects the mechanic who installed the modification; it does not protect the truck owner who operates the modified vehicle.
WHY THE CLEAN AIR ACT STILL PROHIBITS THIS WORK
The Clean Air Act, passed in 1970 and significantly amended in 1990, is the federal statute that governs air quality. Section 203 of the Act explicitly prohibits the removal or rendering inoperative of any emissions-control equipment on motor vehicles. The law applies to manufacturers, aftermarket equipment suppliers, and mechanics who install such equipment. The law is strict: it does not require proof of intentional harm or knowledge of the law’s requirements. Installing a defeat device is a violation regardless of intent. Trump’s pardons do not change this statute. They do not rewrite the Clean Air Act. They do not authorize defeat devices.
What a pardon does is forgive a specific person’s criminal culpability for past violations. It is an executive action that does not bind future law enforcement, state regulators, or civil courts. A state attorney general could theoretically prosecute the same conduct under state environmental law. A vehicle owner could theoretically sue a mechanic for selling them a non-compliant vehicle. The pardons create legal closure for these nine individuals; they do not create legal closure for the broader question of whether defeat devices are acceptable. A significant limitation: pardons are traditionally reserved for cases where enforcement is thought to be unjust or overly harsh. Using pardons to signal disagreement with a particular law is unusual and suggests a potential shift in federal priorities. However, presidential disagreement with a law does not make the law unenforceable. Future administrations could reverse or modify the priority; Congress would need to amend the statute itself to change the legal prohibition.
THE TRUMP ADMINISTRATION’S APPROACH TO ENVIRONMENTAL REGULATION
Trump’s statement on Truth Social characterized the prosecutions as persecution and the defendants’ work as simply “fixing their car.” This framing reflects a particular view of environmental regulation — that emissions rules are overreaching and that vehicle owners and mechanics should have broad latitude to modify their own vehicles. This perspective has support among diesel enthusiasts and in rural communities where large trucks are common and environmental regulation is viewed skeptically. The pardon decision aligns with the Trump administration’s broader deregulatory stance.
In early 2026, the administration had already rolled back several Obama-era environmental rules and signaled skepticism toward EPA enforcement actions. The diesel mechanic pardons sit within this broader policy direction. However, pardoning individuals and eliminating regulations are distinct actions. A pardon forgives past violations; deregulation would require congressional action or an executive order rewriting the underlying statute or rule.
WHAT THIS MEANS FOR DIESEL MECHANICS AND ENTHUSIASTS
For the diesel aftermarket industry, the pardons send a mixed signal. The individuals convicted were not operating in a legal gray area — the Clean Air Act is explicit. The industry had been on notice since at least the late 1990s that defeat devices were illegal. Some shops ceased offering defeat device installations in response to earlier enforcement actions; others continued operating, accepting the legal risk.
The pardons may embolden shops to resume or expand defeat device installations, betting that a future pardon or regulatory change will shield them from enforcement. For individual diesel enthusiasts, the pardons do not change the practical reality: modified vehicles remain non-compliant with federal emissions law and may face civil penalties, registration denial, and potential criminal charges. An enthusiast in a state with rigorous emissions enforcement faces more legal exposure than an enthusiast in a state with minimal enforcement. A truck modified years ago that was never discovered faces ongoing violation risk if detected during a routine inspection or emissions test. The pardon of these nine individuals creates a precedent and a signal about priorities, but it does not eliminate the underlying legal or practical constraints.