“The U.S. Department of Justice has reiterated its warning that state employees are subject to federal prosecution for implementing the state’s medical-marijuana program. . . . In a Feb. 16 letter, Acting U.S. Attorney Ann Birmingham Scheel wrote to Gov. Jan Brewer that her office will continue to ‘vigorously enforce’ federal laws against those who ‘operate and facilitate large marijuana production facilities and marijuana production facilities involved in the cultivation, sale and distribution of marijuana, even if purportedly for medical purposes.’  Scheel said that state employees who participate in the Arizona Medical Marijuana Act ‘are not immune from liability’ “