A tractor mechanic who was fired for using medical marijuana off the job does not have a claim under the Americans with Disabilities Act, a federal judge ruled.In a written opinion, U.S. District Judge Sara L. Ellis of the Northern District of Illinois threw out a lawsuit accusing Dayton Freight Lines Inc. of violating the ADA by discriminating against former employee Gary Hill because he has lung cancer and by denying him a reasonable accommodation that would have allowed him to continue working.Hill is not protected by …