He believed pot was dangerous until his research convinced him otherwise. He then became a leading proponent of legalization.

Dr. Lester Grinspoon, a Harvard psychiatry professor who became a leading proponent of legalizing marijuana after his research found it was less toxic or addictive than alcohol or tobacco, died on June25 at his home in Newton, Mass. He was 92.

His son David confirmed the death.

Dr. Grinspoon was an unlikely crusader for marijuana. At first, he believed that it was a dangerous drug. When the astronomer Carl Sagan, a friend who was also teaching at Harvard, offered him a joint in the late 1960s, Dr. Grinspoon warned him against continuing to smoke it.

“He took another puff and said, ‘Here, Lester, have some,’” he told The Boston Globe in 2018. “‘You’ll love it and it’s harmless.’ I was absolutely astonished.”

Dr. Sagan’s response was, in effect, a challenge. Dr. Grinspoon plunged into a review of existing research, hoping to find studies that agreed with his view of marijuana’s medical risks. He found that 19th-century physicians prescribed marijuana for pain and to help people sleep, but he found nothing to back decades of hysteria that marijuana was addictive, the view embodied in the lurid 1936 film “Reefer Madness” (originally called “Tell Your Children”) and the federal government’s decision to make it illegal a year later. [Read More @ The New York Times]