Buyers’ clubs that specialize in importing foreign drugs are, for the most part, legal to operate. Because they are usually nonprofit and carefully document that all medications are resold to patients under the supervision of a doctor, U.S. customs officials rarely interfere with their operation. Yet, most of the drugs sold by buyers’ clubs have not been tested under FDA supervision and are not guaranteed to be either safe or effective. Other buyers’ clubs include those that exclusively sell marijuana to patients with chronic diseases such as HIV/ AIDS. Unlike buyers’ clubs that sell pharmaceutical drug products, most cannabis buyers’ clubs are in a state of constant legal limbo. For example, a cannabis buyers’ club in San Francisco has been supported by the city’s government but is considered illegal by the California state government, and all three entities have been involved in legal wrangles. Cannabis buyers’ clubs in other cities either operate illegally or have not yet been discovered or investigated by the authorities. Most cannabis buyers’ clubs require that their marijuana-purchasing clients enroll as members in the club. This often requires a potential customer to present a certified doctor’s note or prescription stating the reason that marijuana is necessary.