Cannabis advocates are circulating a document that shows the head of the World Health Organization is advocating for the reclassifying of cannabis and various by-products to lessen international legal barriers to consumption and research.

The document, which has not yet been officially released, recommends relaxing a 1961 international treaty that classified cannabis as a dangerous drug.

"The practical effects of the changes would be somewhat limited, in that they wouldn't allow countries to legalize marijuana and still be in strict compliance with international treaties, but their political implications are hard to overstate," Angell wrote explaining the document in a piece for Forbes magazine.

"Taken together, recommendations, if adopted, would represent a formal recognition that the world's governing bodies have effectively been wrong about marijuana's harms and therapeutic benefits for decades."

Members of the United Nations would vote on the WHO letter. Prospects for passage of that vote—and where the U.S. would come down—are unclear. President Donald Trump's remarks about cannabis have reflected cautious support and he recently fired his former Attorney General Jeff Sessions, an outspoken opponent of legalization.

The WHO letter comes at a time of renewed debate in the U.S. about the safety of cannabis sparked by the publication last month of a new book that argues that high-potency cannabis may exacerbate mental illness and increase violence.