In the case of Barbuto v. Advantage Sales and Marketing, LLC the court ruled in favor of the plaintiff. The court showed a violation of terminating the plaintiff for lawful use of medical marijuana. The defendants Human Resource Team informed the plaintiff that their policy followed the federal law, not state law. The plaintiff sought a remedy through claims of handicap discrimination. You can read more details of this case at http://masscases.com/cases/sjc/477/477mass456.html
This case emphasizes the need to consult with your legal team on reviewing your Drug Screening policy.