The White House announced on Friday that President Trump had issued pardons to 11 men, most of whom had been convicted of crimes related to the Clean Air Act, a bedrock environmental law.
The president also pardoned Adam Kidan, a major donor to Republicans, including Mr. Trump. He had served about two and a half years in prison for his role in a fraud scheme involving the disgraced former lobbyist Jack Abramoff.
The Clean Air Act pardons benefited people who had sold or installed devices for diesel trucks that defeated their emissions controls, making them far more polluting. It was the latest move by the Trump administration to undermine laws intended to fight climate change and curb air pollutants that harm human health.
Republicans and their allies in the business community have cast enforcement of the Clean Air Act as a hindrance to commerce and an undue burden to those who rely on diesel engines.
Mr. Trump, in a social media post announcing some of the pardons on Friday afternoon, echoed that framing, minimizing the scale of the crimes and casting the law, which was first enacted in 1963, as a tool used by his predecessor to target political enemies.
“It is my Great Honor to have just signed Pardons for six people who were persecuted by the Biden Administration, and were in, or being sent to, prison, for ‘fixing their car,’” Mr. Trump wrote on Truth Social.
A White House official subsequently provided a list of the pardon recipients. It included nine people who had been charged with infractions related to the Clean Air Act.
The systems that most of them were accused of disabling are intended to make tailpipe emissions cleaner.
But the systems put more strain on engines, and malfunctions can lead to engine shutdowns, particularly in cold weather. Some truck owners have turned to mechanics — like some of those who were pardoned — to install devices to defeat the systems.
In January, the Justice Department announced that it would stop prosecuting Clean Air Act violations as criminal offenses, describing such cases as an example of the “overcriminalization of federal environmental law.” The department said it would continue to pursue civil enforcement.
Mr. Trump went a step further on Monday, issuing a directive to the Environmental Protection Agency, which oversees enforcement of the act, that could pave the way for people to tweak emissions controls on their own vehicles without fear of civil penalty. The directive indicated that it was intended to “reduce or remove these burdensome regulations and decrease the rising costs that consumers face.”
A number of people who had been convicted criminally have been openly seeking clemency from Mr. Trump, including by enlisting Jeff Daugherty, a political consultant and lobbyist from Cheyenne, Wyo.
He had assisted Troy Lake, a diesel mechanic who served months in prison for a Clean Air Act violation before Mr. Trump freed him with a pardon in November.
Mr. Daugherty represented five of the men who were pardoned on Friday, according to lobbying filings.
“These guys should never have been felons, ever,” Mr. Daugherty said.
One of his clients who was pardoned on Friday was Mackenzie Spurlock, 31, the owner of Matanuska Diesel, a small shop in Wasilla, Alaska.
He was charged with collecting at least $30,000 for removing emissions controls from at least 20 vehicles.
He pleaded guilty last year and was sentenced to probation and fined $32,000. The conviction prevented him from rejoining the National Guard, where he spent six years as an aircraft mechanic.
“It’s a huge relief,” Mr. Spurlock said after the pardon was announced. He said he was grateful to the president as well as to Senator Dan Sullivan, Republican of Alaska, who had supported the clemency grant.
With the timing of the pardon the day before the 250th anniversary of the country’s independence, Mr. Spurlock said that “driving past, seeing flags wave today just hits completely differently.”
He said that he planned to re-enlist in the National Guard, and would like to work with federal agencies and manufacturers to address the persistent issues that lead vehicle owners to seek out so-called defeat devices.
He has argued that modern emissions control systems often render trucks inoperable in Alaska’s harsh winters, leaving drivers stranded in subzero temperatures. He said he was simply trying to help his customers by installing the devices.
But the cumulative effect of bypassing emissions systems adds up.
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 diesel pickups to American roads, spewing harmful nitrogen oxides at levels up to 300 times the legal limits.
Environmental groups immediately criticized the pardons.
“Making kids sicker with asthma by poisoning the air is unpardonable,” Dan Becker, director of the Safe Climate Transport Campaign at the Center for Biological Diversity, said in an email. “But that’s what Trump is crowing about on this 100F degree day in globally warming Washington as he issues get out of jail free cards for pollution cheaters!”
Mr. Kidan had pleaded guilty in 2005 to conspiracy and fraud charges involving his purchase of a casino boat fleet with Mr. Abramoff, who became a poster child for Washington corruption in the pre-Trump era.
Mr. Abramoff and Mr. Kidan were each sentenced to 70 months in prison and ordered to pay a total of $21.7 million in restitution related to the $147.5 million purchase of a cruise ship line in 2000.
Mr. Kidan served less than half of that prison sentence and became an executive in the staffing industry.
It is not clear whether he paid the full amount of the restitution. A pardon typically wipes away any remaining financial obligations.
He has donated millions of dollars to Republican campaigns and groups over the years, including more than $270,000 to Mr. Trump’s political committees in 2024, according to campaign finance records.
Mr. Kidan declined to comment.
Maxine Joselow contributed reporting.
