Put in your own words: Although an employer can generally require job applicants to submit to drug testing, an employer's right to test current employees is less clear. No federal law specifically authorizes drug testing of employees, except for certain workers in the defense and transportation industries. Many state laws, however, limit the circumstances under which an employer may test for drugs and the types of tests an employer may conduct. If your employer wants to conduct a drug test, look into your state's law, because the rules vary from state to state. (Contact your state labor department for more information.) What is acceptable in one state may not be acceptable in another. That being said, your employer is most likely to be on sure legal footing if it limits testing to: workers whose jobs carry a high risk of injury to themselves or others (such as a pilot or a security guard who carries a gun) workers who have been involved in an accident that suggests the possibility of drug use (for example, a delivery driver who causes a collision by driving erratically) workers who are currently in or have completed a rehabilitation program, and workers whom a manager or supervisor reasonably suspects are using drugs (based on, for example, obvious signs of impairment such as slurred speech or glassy eyes)