Screening for Drugs By Employers Drug testing is the process of screening one's urine (urinalysis), hair, or other parts that would reveal the use of illegal substances. It is often used in corporations and jobs involving the use of machinery. For years now, people have been taking drug tests for the sake of keeping a job. These tests have been around for nearly forty years, but the question still arises today: are they really necessary? It is very difficult to determine whether drug tests add or detract from problems in society. In a case where a man uses illegal substance and proceeds to operate a six thousand pound crane, drug