Police learned that marijuana was being distributed from D's home. From newspaper articles and the Internet, police discovered D claimed to be engaged in medical marijuana activity. Police set up surveillance on the home and questioned people who came from that home. All but one of the subjects questioned had a medical marijuana recommendation-but that one person had a cooperative card from the Oakland Cannabis Buyers' Cooperative. Detective Sue McCurry was sent into D's residence without a medical certificate in an attempt to buy marijuana. She was unsuccessful. D told police that he planned to establish a medical marijuana cooperative like the ones operating in the San Francisco Bay Area. D claims he created a legal cooperative to grow and supply medical marijuana for himself and others for use under the Compassionate Use Act of 1996. Eventually, D was arrested. P asserts D and his codefendant, Rodger, were illegally cultivating and selling marijuana. D’s proffer of evidence that his actions were based on a good faith belief in mistake of law. During trial, the trial court repeatedly rebuffed D's attempts to argue and present evidence that he believed the formation and operation of the cooperative was legal. The court also excluded evidence of how other cooperatives operated in other communities to demonstrate that defendant believed his conduct was legal. D asked and the court refused to instruct the jury on the defenses of mistake of law and the vagueness of the Compassionate Use Act. The jury acquitted D of cultivating marijuana, sale of marijuana and being a felon in possession of ammunition. The jury found D guilty of conspiracy to sell marijuana and being a felon in possession of a firearm and ammunition. D appealed. D argues, in part, he “was denied his constitutional right to present a mistake of law defense to the conspiracy charge” and “the court erred by denying his request to have the jury instructed concerning his claim that the governing law was too vague to give adequate notice.”