Forensic psychiatry is a sub-speciality of psychiatry. 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.

Court work

Forensic psychiatrists work with courts evaluating an individual's competency to stand trial, defences based on mental diseases or defects (e.g., the "insanity" defense), and sentencing recommendations. There are two major areas of criminal evaluations in forensic psychiatry. These are Competency to Stand trial (CST) and Mental State at the Time of the Offence(MSO).

Competency to stand trial (CST)

This is the competency evaluation to determine that a defendant has the mental capacity to understand the charges and assist his attorney. This is seated in the Fifth Amendment to the US Constitution, which ensures the right to be present at your trial, to face your accusers, and to have help from an attorney.

In English and Welsh law a similar concept is that of "fitness to plead".

As an expert witness

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.