A recent report from the Center on Addiction and Substance Abuse, the prohibitionist propaganda mill headed by former Secretary of Health, Education, and Welfare Joseph Califano, is titled "Non-Medical Marijuana: Rite of Passage or Russian Roulette?"
The use of the awkward adjective non-medical is supposed to reassure you that Califano is not the sort of extremist who would deny cannabis to cancer or AIDS patients. But he is the sort of extremist who would compare pot smoking to a game in which players face a one-in-six chance of sudden death.
In a statement released along with the report, Califano declared that "teens who smoke marijuana are playing a dangerous game of Russian roulette." This grim sport is not limited to kids, according to Califano, who continued, "Parents who mistake the absence of proof for the proof of absence are playing Russian roulette with their children's lives."
So you can avoid this error, here is a clue for telling the two apart: The absence of proof is the problem with the CASA report, while the proof of absence is the wild rhetoric that indicates a lack of scientific seriousness.