Medical marijuana, in virtually every state where it is legal, operates under a set of rules not applied to such drugs as Oxycontin and Percocet. You can get fired from your job if you test positive for marijuana regardless of your medical status. You may not be allowed to use or possess marijuana if you are on probation. You'll pay taxes on your legal purchase of this legal medicine. In other words, most states seem to take a wink-wink approach to marijuana as medicine, implying that while it is legal it really isn't medicine and won't be treated as such.