Forensic psychiatry is a sub-speciality of psychiatry and an auxiliar science of criminology. It encompasses the interface between law and psychiatry. A forensic psychiatrist provides services – such as determination of competency to stand trial – to a court of law to facilitate the adjudicative process.
Forensic psychiatrists are often called to be expert witnesses in both criminal and civil proceedings. Expert witnesses give their opinion about a specific issue. Often the psychiatrist will have prepared a detailed report before testifying. The primary duty of the expert witness is to provide an independent opinion to the court. An expert is allowed to testify in court with respect to matters of opinion only when the matters in question are not ordinarily understandable to the finders of fact be they judge or jury.