They could be covered by state laws affecting who may or may not be tested.
Related rulings include approving testing for railroad operators, police officers and medical professionals who care for patients. Generally, where "a position has a direct affect on safety, random testing has been allowed" (National Workrights Institute). Attempts to spread drug testing to non-safety positions like janitors and clerical workers have been unsuccessful.
The U.S. Supreme Court, in Washington v. Davis, 426 U.S. 229 (1976), ruled that the District of Columbia's Test 21 (Question 2) was not discriminatory, even though it screened out many more black police force applicants than whites and had not been proved relevant to on-the-job performance. The test itself could not be blamed for the low black population on the police force. There had been no direct evidence that the D.C. police force was actively excluding black recruits, and the test was widely used for other government jobs. The Supreme Court stated in the ruling that a statute is not discriminatory "if in practice it benefits or burdens one race more than another" when it is designed to serve race-neutral goals such as a verbally competent work force, unless there is compelling evidence to the contrary. The high court feared that such a standard could be used to invalidate a wide range of laws that affect different groups disproportionately.
The Louisiana Court of Appeals ruled in Lam