Commission of Oyer and Terminer Law and Legal Definition

In History, commission of Oyer and Terminer is a royal appointment authorizing a judge to go on the assize circuit and hear felony and treason cases. Under the commission of Oyer and Terminer, the judges can only proceed upon an indictment found at the same assize and before themselves, as the judges are directed to inquire as well as to hear and determine the same. However, they must first inquire by means of the grand jury or inquest, before they are empowered to hear and determine by the intervention of the petit jury.