Criminalization of marijuana, psychedelic mushrooms and other psychoactive drugs in the United Kingdom amounts to an act of scientific censorship that inhibits further research from being done, according to a leading researcher on the effects of drugs on the human brain.

Outlawing of psychoactive drugs amounts to "the worst case of scientific censorship since the Catholic Church banned the works of Copernicus and Galileo," said David Nutt, a professor of neuropsychopharmacology at Imperial College London, in a statement accompanying a paper published in the journal Nature Reviews Neuroscience.

Nutt said that the perceived dangers of the drugs and the harm they cause is overstated, according to Reuters, which obtained a copy of Nutt's remarks.

"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," he said.

Nutt has caused some controversy in the past for expressing views contrary to government drug policy while acting as a government advisor, prompting his 2009 dismissal from his position on Britain's Advisory Council of the Misuse of Drugs.

In their paper, Nutt, Leslie King -- another former drug advisor -- and University of North Carolina's David Nichols called for the use of psychoactive drugs in research to be exempted from severe restrictions.

The paper, which was published to coincide with a conference on scientific research on psychedelics, points to evidence of unexplored medicinal benefits in cannabis, MDMA and psychedelics such as LSD and psilocybin, the compound found in magic mushrooms.

"If we adopted a more rational approach to drug regulation, it would empower researchers to make advances in the study of consciousness and brain mechanisms of psychosis, and could lead to major treatment innovations in areas such as depression and PTSD," Nutt said.

An abstract of the paper, "Effects of Schedule I drug laws on neuroscience research and treatment innovation" can be found here.