A key paper cited to explain WADA’s decision to place marijuana on the prohibited list is a 2011 review article by two members of the agency and a toxicologist at the U.S. National Institute on Drug Abuse. In it, the authors state that, based on the animal and human studies that were available at the time, “cannabis can be performance enhancing for some athletes and sports disciplines.”

Margaret Haney, a professor of neurobiology who studies the effects of cannabis at the Columbia University Irving Medical Center, says the data the authors used to support that stance in the paper are “really not impressive at all and almost contradict what they claim.” For instance, she notes, the article cites a study of cyclists that reported that endurance was slightly reduced after consuming weed.

Since 2011 there have been several published review papers in which researchers evaluated the available research on this issue. Many of them—including one co-authored by the current medical director of WADA—have come to the same conclusion: no convincing evidence exists that cannabis can make athletes better at their sports.

“I think the consensus, in the absence of clear-cut information, is that cannabis is more likely to be viewed as performance-detracting rather than performance-enhancing,” says David McDuff, a sports psychiatrist and professor at the University of Maryland, who is also a member of the International Olympic Committee’s Mental Health Workgroup.