In a significant departure from the policy of the George W. Bush administration, Attorney General Eric Holder has instructed federal prosecutors to stop prosecuting those who use marijuana for medical purposes in the 13 states where it is legal.
Thus far, prosecution was possible because of the 2005 Supreme Court ruling stating the federal government could continue to enforce U.S. law barring the cultivation, possession and use of marijuana, even in states that had legalized it.
Holder said that "it will not be a priority to use federal resources to prosecute patients with serious illnesses or their caregivers who are complying with state laws on medical marijuana."
However, he added that law enforcement will still go after traffickers "[hiding] behind claims of compliance."
Advocates of legalizing marijuana, who argue it may help treat chronic pain and nausea, have praised the government for the decision.
"This change in policy moves the federal government dramatically toward respecting scientific and practical reality," said Bruce Mirken of Marijuana Policy Project, quoted by the Associated Press.
However, critics have claimed it will weaken law enforcement in their fight against Mexican drug cartels.
During his presidential campaign, Barack Obama promised he would not prosecute medical marijuana users in states where the practice was legal under state law.