The Judge Advocate General (JAG) is the chief judge of the Court Martial, which tries Service men and women for serious criminal offences, and the Office of the Judge Advocate General (OJAG) is a part of the Judicial Office. This section within the Courts and Tribunals Judiciary website (the Judicial Office’s site) provides what is described as an informal guide to the Service justice system, together with official guides to Court Martial practice, procedure and sentencing.