The US government is to announce that it will allow more research into cannabis, but has rejected requests to relax the classification of the substance as a dangerous, highly addictive drug with no medical use, according to sources with direct knowledge of the matter.
The decision is the Drug Enforcement Administration's response to a 2011 petition by two former state governors who had urged federal agencies to re-classify cannabis as a drug with accepted medical uses, the two sources said on Wednesday (local time). They requested anonymity because they were not authorised to discuss the matter publicly.
The DEA declined to comment. However, earlier on Wednesday the agency had sent emails, a copy of which was reviewed by Reuters, to parties that had expressed an interest in the matter, saying it would be making "important announcements regarding cannabis related topics" on Thursday.
The Food and Drug Administration did not respond immediately to requests for comment.
For decades, cannabis has been classified as a "Schedule I" drug with "no currently accepted medical use and a high potential for abuse," on par with heroin. The government has repeatedly rejected appeals over the years to reclassify cannabis. Loosening that definition could encourage scientific study of a drug that is being used to treat diseases in several US states despite little proof of its effectiveness.
Twenty-five states have sanctioned some forms of cannabis use for medical purposes. Four states - Alaska, Washington, Oregon, and Colorado - and the District of Columbia have gone even further, allowing its recreational use for adults.
California and eight other states have recreational or medical cannabis proposals headed for their 2016 ballots.
A drug can be reclassified through congressional legislation or a formal scheduling petition process that involves medical and scientific evaluation by the FDA and DEA.
The DEA only allows cannabis for federally sanctioned research to be cultivated at a garden at the University of Mississippi, an operation overseen by the National Institute on Drug Abuse.
Cannabis advocates have long argued that this arrangement, and the labeling of cannabis as among "the most dangerous drugs" under the Controlled Substances Act, has sharply limited the supply available for research.
The sources said the federal government would pave the way on Thursday for increased research, possibly with cannabis supplies from outside the University of Mississippi.
"This is a good day for science," said Kevin Sabet, president of Smart Approaches to Marijuana, a group that opposes legalisation. "This shows that the federal government is flexible on legitimate research but is nowhere near wanting to legalise marijuana."