Ever heard someone argue against medical marijuana on the grounds that there hasn’t been enough research to prove that it works? There's been plenty, of course, but there would be even more if the government weren't spending all its grant money trying to prove that marijuana is poisonous instead of therapeutic:

The Medical College of Wisconsin will investigate the effects of chemicals in marijuana on the development of psychiatric disorders thanks to $1.7 million grant from the National Institute of Health's National Institute on Drug Abuse.
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Using lab research and mouse models, this study will test the hypothesis that the primary psychoactive chemical in marijuana produces an over-activation of an enzyme in the brain and that this is responsible for the increased incidence of psychiatric disorders in marijuana users.

Last I checked, the "primary psychoactive chemical in marijuana" is widely available in an FDA-approved pill that the National Institute on Drug Abuse has never lobbied to take off the shelves. How concerned could they possibly be about the dangers of THC if they let doctors prescribe it to people?

The sick truth here is that their only agenda is to create negative headlines about marijuana, not to discover anything of actual scientific significance. That's why they spend their money dosing rats with powerful synthetic chemicals instead of studying the massive population of real medical marijuana patients who are using it successfully to treat a variety of illnesses.