A U.S. attorney’s office says it will now begin “rigorously” prosecuting people over simple possession or use of marijuana on federal lands after the Trump administration rescinded Biden-era guidance that advised against taking such legal actions.

The U.S. Attorney’s Office for the District of Wyoming said in a press release on Thursday that the Justice Department “rescinded previous guidance concerning the prosecution of simple marijuana possession” in a memo to prosecutors on September 29.

“This comes after President Biden pardoned certain U.S. citizens and lawful permanent residents for offenses related to simple possession, attempted possession, or use of marijuana and directed U.S. Attorney’s [sic] not to prosecute those offenses,” it said. “This significantly curtailed federal prosecutions of misdemeanor marijuana offenses.”