A worker lives in a state where medical marijuana can be obtained through a doctor's prescription. You are an auditor for a major restaurant chain. You work for the franchisor and must drive long distances to perform on-site sales verifications at various retail franchise locations.
Because of occasional, debilitating back spasms, you smoke marijuana during the late evening in accordance with your doctor's directions.
Would it ethical for your employer to force you to take a test for substance abuse that detects, among other things, marijuana use?