This JAMA viewpoint article examines how Medical Boards may look at physicians who recommend marijuana and the inconsistencies between state and federal laws.  There are some interesting facts on usage and indications.

During the past 2 decades, attitudes and laws have become more tolerant toward marijuana, with the prevalence of adults reportedly using the substance increasing from 4.1% in 2001 to 9.5% in 2013.2 Although there is little evidence for the efficacy of marijuana in treating certain medical conditions, marijuana has been variously suggested for alleviating some or all symptoms of a range of debilitating medical conditions, including but not limited to certain types of cancer, multiple sclerosis, Alzheimer disease, posttraumatic stress disorder (PTSD), epilepsy, Crohn disease, and glaucoma.3

Source: Medical Board Expectations for Physicians Recommending Marijuana | Clinical Pharmacy and Pharmacology | JAMA | The JAMA Network