The problem with recent medicinal marijuana legislation is that it's not based on actual research. States are deciding certain diseases can be treated with pot, but because the federal government has classified marijuana as an illegal and dangerous drug, research on its health benefits are sparse. It's a catch-22 manufactured by the Drug Enforcement Agency: marijuana is illegal because the DEA says it has no proven medical value, but researchers have to get approval from the DEA to research marijuana's medical value.
As Catherine Saint Louis at The New York Times explains, research has shown that marijuana can alleviate pain and nausea symptoms in people with cancer, H.I.V./AIDS and multiple sclerosis. But medical marijuana laws in several states, including the heavily regulated bill just passed in New York State, also allow marijuana to be prescribed for Parkinson’s disease, Lou Gehrig’s disease and epilepsy, despite there being no high-quality studies supporting the health benefits. In some states the lists go on and on, in an attempt to be inclusive without allowing pot for "headaches" and "pain."
“I just don’t think the evidence is there for these long lists,” Dr. Molly Cooke, a professor of medicine at the University of California, San Francisco, told The Times. “It’s been so hard to study marijuana. Policy makers are responding to thin data.”