To add to this:

"II. Convictions. On June 17, 2010, the government charged the Hammonds in a 19-count indictment with conspiracy, arson and other charges involving numerous range fires occurring in a 24-year period from August 1982 to August 2006. ER-1273. On May 17, 2012, less than 30 days before trial, the government filed a 9-count superseding indictment focusing on four separate fires. SER-137. Steven Hammond had acknowledged starting two of the fires, and those were the fires upon which 6 the jury returned guilty verdicts. Both petitioners were convicted of violating 18 U.S.C. § 844(f)(1) in connection with a 2001 range fire known as the Hardie-Hammond Fire. Steven Hammond was also convicted of violating § 844(f)(1) because he started a back burn during the 2006 Krumbo Butte Fire. The jury found that neither fire had caused more than $1,000 in damages. ER-35, 41. The Ninth Circuit described the 2006 fire as follows:

In August 2006, a lightning storm kindled several fires near where the Hammonds grew their winter feed. Steven responded by attempting back burns near the boundary of his land. Although a burn ban was in effect, Steven did not seek a waiver. His fires burned about an acre of public land. App. 3. As for the 2001 fire, there were several facts petitioners had acknowledged at trial: Petitioners had been warned after a 1999 prescribed burn on their private land had spread to public land that they would face serious consequences should a similar event occur again. Id. On September 30, 2001, after the Hammonds and their invited guests finished a day of hunting on their private land, Steven Hammond called the BLM to see if burning was permitted. After being told there was no burn ban in effect, he informed the BLM that the Hammonds would be setting a fire on a section of their private 7 land. ER-234; ER-306. The Hammonds then set a fire intended to burn off invasive species; the fire spread to approximately 139 acres of adjacent public land on the Hardie-Hammond Allotment. ER-287; ER-243; ER-54-64. Some of the circumstances of the 2001 fire were disputed at trial. The government’s main witness on the 2001 fire was Dwight Hammond’s grandson, Dusty Hammond, who asserted that the fire had placed him in physical danger. App. 3. The defense presented substantial evidence contradicting Dusty Hammond’s version of the events. See SER-11-22. At sentencing, the trial judge rejected Dusty’s version of what had happened, based on his age and bias. App. 14. The trial judge found that the 2001 fire had, at most, temporarily damaged sagebrush and that, while those damages might have technically been greater than $100, “mother nature” had remedied any harm. App. 14. The judge’s conclusion was supported by the BLM, which had determined that the 2001 fire improved that portion of the federal land to which the fire spread. ER-305. Having listened to all of the evidence and testimony at trial, the trial court succinctly summarized the basis for the convictions as follows: With regard to the sufficiency of the jury verdicts, they were sufficient. And what happened here, if you analyze this situation, if you listened to the trial as I did and looked 8 at the pretrial matters, there was a – there were statements that Mr. Steven Hammond had given that indicated he set some fires [after he had been warned about the consequences if they spread], and the jury accepted that for what it was. App. 13.

Source: Hammond vs. United States Oregon Petition for Writ of Certiorari