The problem with the "medical marijuana" debate is that the pro-legal forces are being intellectually dishonest. No reputable doctor would EVER prescribe a medicine like marijuana, which is a cocktail of more than 40 active chemicals, some of which are carcinogenic.
Now, separating ONE chemical, doing research and clinical trials on it that are based on science is a good idea.
The anti-legal forces fear, correctly, that the agenda underlying "helping the sick people" has to do with recreational use of marijuana rather than medical use. Obviously being able to grow it yourself for "medical reasons" is de facto legalization, since cops won't be able to the intentions of the grower.
The PARS method is credible. Other methods that involve smoking the whole thing are not.
Probably not formally prescribe, but certainly many doctors have suggested to their patients that marijuana might be helpful for, among other things, reducing nausea and other side effects from chemo.
The real problem is that drug companies would much rather sell their own 'engineered' product for $100's/month than let a patient use something that could be grown for a tiny fraction of that cost.
Besides, while pot probably isn't as harmless as its proponents claim, the hysteria surrounding it is way overblown. People complain about "today's pot is 100 zillion times more potent than that of 40 years ago", but fail to realize that much of the push for more potent strains has been a result of the drug war. During prohibition, hard liquor was more popular than beer; today, the reverse is true.
The real "problem" with pot is that, were it legal, it could threaten many industries with unwanted competition. Not sure how to solve that 'problem', though...