There are important differences between general and forensic psychiatry. In forensic psychiatry the psychiatrist serves a third party rather than the patient; both the patient and the psychiatrist must understand this to avoid misrepresenting the doctor's role to the patient and to enable the doctor to adequately serve the law. Psychiatric opinions that are useful for treatment may not be useful in determining whether a person can be considered responsible or competent. In forensic work the psychiatrist's role is not that of a therapist; it is that of an evaluator and an opinion giver but not a decision maker.