How many states allow the use of marijuana for medical reasons? Is the supreme court going to overrule them?

Since 1996, nine states - Alaska, Arizona, California, Colorado, Hawaii, Maine, Nevada, Oregon and Washington - have passed laws providing that patients who use marijuana under their doctor's supervision will not be prosecuted under state laws. To date, federal officials have not challenged the legality of any of those measures. Nor has the federal government successfully prosecuted any doctors for prescribing marijuana to their patients. One federal court has said a physician's right to discuss marijuana therapy with a patient is constitutionally protected. However, there is no lawful way to distribute or fill a prescription for marijuana. The Supreme Court last week heard arguments in a case which will decide whether medical marijuana distributors may use a "medical necessity" defense in federal court if they can prove that their clients are seriously ill and have a legitimate medical need for the substance. It is not expected that the laws allowing the use of marijuana for medical purposes will be overturned. But until the government also allows someone to provide that marijuana, the benefits the laws were meant to convey may be largely illusory.