The official records of many of the most important 'state trials', mainly for treason, held between 1477 and 1813, including those of Sir Thomas More, Queens Anne Boleyn and Katharine Howard, Guy Fawkes, the Regicides and the Jacobite rebels of 1715 and 1745.

A few are ordinary term indictment files, removed from what is now KB 9, but most are either files of special commissions of oyer and terminer or of the court of the lord high steward and peers. Both were specially commissioned courts, the latter having the particular function of trying peers accused of treason.