With 23 states and the District of Columbia now having legalized medical marijuana, physicians should know the scientific rationale and the practical implications for its use. A recent review published in JAMA, however, found that the quality of evidence supporting the drug's efficacy for certain conditions is questionable. U.S. doctors and teaching hospitals received $6.49 billion from drug and medical-device makers in 2014, according to new government data. By disclosing information on the payments, theU.S. is seeking to bring transparency to the financial relationships between drugmakers and health care providers.