Outlawing psychoactive drugs such as marijuana and “magic mushrooms” impedes research and amounts to scientific censorship, according to three researchers. The harms of these drugs have been overstated in many cases, according to David Nutt, a professor of Neuropsychopharmacology at Imperial College London.

In Nature Reviews Neuroscience, Nutt and Leslie King, also from Imperial College, and David Nichols of the University of North Carolina, argue the decision to outlaw these drugs was based on their perceived dangers at the time. “The laws have never been updated despite scientific advances and growing evidence that many of these drugs are relatively safe. And there appears to be no way for the international community to make such changes,” Nutt said.

According to Nature World News, Nutt said the outlawing of psychoactive drugs amounts to “the worst case of scientific censorship since the Catholic Church banned the works of Copernicus and Galileo.”

Nutt said if researchers were allowed to study the effects of psychoactive drugs, they could make advances in the study of consciousness and brain mechanisms of psychosis, potentially leading to new treatments for depression and post-traumatic stress disorder.

Last year, Nutt published two small studies on psilocybin, also known as magic mushrooms. He said the findings may help scientists develop treatments for depression. Reuters reports Nutt announced in April he was stymied in his attempt to conduct a full clinical trial of psilocybin for depression because of the stringent rules on the use of illegal drugs in research.