Since the emergence of hypnosis as an investigative tool of police work, lobbying and propoganda by the medical profession has attempted to deny law enforcement the right to employ investigative hypnotists, arguing that the practice of hypnosis should be limited to trained psychologists and psychiatrists. Medical and forensic hypnosis, however, have different goals, and clearly distinct procedural and technical constraints under which hypnotic practices are valid. Forensic hypnotists require 40 or more hours of training, that includes the particulars of investigative hypnosis, of which medical practitioners are ignorant. This is illustrated by a hypnotic session held for forensic purposes by a psychiatrist who committed numerous procedural and technical errors that rendered the obtained testimony inadmissible in court. The protection of a witness from contamination during hypnosis is the dominant concern of this form of investigation. The investigator should not know the details of the case, the interview should be recorded in its entirety, and the subject should relate a free, uninterrupted narrative account of the event under investigation twice -before and during the hypnotic state. The suggestibility of the subject remains high even after the termination of the hypnotic ritual and the trained forensic hypnotist must guard against obtaining evidence in a way that makes the interview vulnerable to defense challenges. The medical profession has not documented evidence of hypnosis by investigators resulting in physical or emotional harm to their subjects or in wrongful convictions or dismissals. Trained and qualified enforcement personnel are being prepared at the Regional Police Academy at Arlington, Texas. Five references are given.