The crime carried a mandatory minimum sentence of five years, but the judge presiding over the case said: "I am not going to apply the mandatory minimum and because, to me, to do so under the Eighth Amendment would result in a sentence which is grossly disproportionate to the severity of the offenses here".
Dwight Hammond, 76, and his 49-year-old son Steven, had served their sentences - Dwight 3 months and Steve 1 year - for setting a backfire on their property that burned a section of land claimed by the federal government.
In 2012, Dwight Hammond and his son Steven Hammond were convicted of committing arson on federal land on two separate occasions.
Now, it turns out not only did the Hammonds get to leave prison early, they also got a ride home in a private jet owned by Vice President Mike Pence's ally, oil company owner Forrest Lucas. The elder Hammond said he was trying to fend off invasive species.
Ammon Bundy on Tuesday called the pardon "long overdue". "For Dwight to spend his remaining years with his wife". "That's all we want is we want 'em home and we want to be able to have a life back".More news: Trump scolds Europe on gas
More: Can Trump really do that? Now that it's come, the pardon gives legitimacy to the occupation he and his brother spearheaded in 2016, Bundy said.
"We brought it to the attention of the vice president, " said David Duquette, a Hermiston resident who serves as national strategic planner for the advocacy group Protect the Harvest.
Tensions have subsided since the 2016 takeover.
Trump has also said on Twitter he could pardon himself in case he would be convicted as a result of Special Counsel Robert Mueller's investigation into alleged Russian meddling in the 2016 United States presidential elections. "The Bundys had nothing to do with them getting out".
Prosecutors alleged in the indictment at the time that the Hammond family set fire to the rangeland after complaining the BLM was taking too long to complete required environmental studies before conducting controlled burn operations.
"They now think they have a friend in the White House who does not value public lands", said Aaron Weiss, media director for the Center for Western Priorities, a nonprofit that advocates protecting public land.More news: Croatia not just about Modric | FIFA World Cup | Croatia | France | Modric
"We think this sends a very unsafe message that will put America's park rangers, law enforcement officers and public land managers at risk", he said.
Williams argued the Hammonds' sentences follow the law and are not excessive, considering the danger in which the Hammonds' actions placed the hunters and the firefighters. "They know they can get away with it", he said.
Congressman Greg Walden, R, also lobbied hard for clemency.
Some of his pardons, including Tuesday's, have been considered controversial by people critical of his policies.
Backcountry Hunters & Anglers' president Land Tawney said that while it is understandable that the ranchers' supporters were anxious for them to be released, the fact that Trump pardoned them outright rather than commuted their sentences "sends a message of tolerance for lawbreakers who could diminish our public lands and waters".More news: Duchess Of Sussex's Sleek Suit Will Look Familiar To Brit Royal Fans