While U.S. officials defend their monopoly, critics say the government is hogging all the pot and giving it mainly to researchers who want to find harms linked to the drug.

U.S. officials say the federal government must be the sole supplier of legal marijuana in order to comply with a 1961 international drug-control treaty. But they admit they’ve done relatively little to fund pot research projects looking for marijuana’s benefits, following their mandate to focus on abuse and addiction.

“We’ve been studying marijuana since our inception. Of course, the large majority of that research has been on the deleterious effects, the harmful effects, on cognition, behavior and so forth,” said Steven Gust, special assistant to the director at the National Institute on Drug Abuse, which was created in 1974.