The Court of the Earl Marshal of England was by the 14c a court with jurisdiction over a wide range of military matters, such as discipline in the army, treason, also prisoners of war and disputed heraldic arms. What remains is the jurisdiction over heraldic arms according to the law of arms. The title of Earl Marshal is now hereditary in the line of the dukes of Norfolk.
Dictionary of Medieval Terms and Phrases. Christopher Coredon with Ann Williams.