1 If you work for the federal government or your company contracts with the federal government, medical marijuana use is definitely not allowable, no matter what state you’re in or what protections you have. 2  This is because federal law (the Drug-Free Workplace Act) trumps any state laws. If you work for the federal government or your company contracts with the federal government, medical marijuana use is definitely not allowable, no matter what state you’re in or what protections you have. 2  This is because federal law (the Drug-Free Workplace Act) trumps any state laws.