Which institution tried and punished heretics in medieval Europe?

The institution that tried and punished heretics in medieval Europe was the Inquisition.

The Medieval Inquisition developed in the late 12th and 13th centuries as a system of Catholic ecclesiastical tribunals investigating suspected heresy. It responded especially to Catharism in southern France and Waldensian movements in parts of France and Italy. Inquisitors gathered testimony, examined suspects, and judged whether beliefs contradicted Church teaching.

The Inquisition was not one permanent court with a single headquarters. It included episcopal inquisitions, later papal inquisitions, and regional tribunals with varying powers and procedures. Pope Gregory IX appointed many Dominican and Franciscan friars as inquisitors during the 13th century.

A common mix-up is treating the Inquisition as identical to the Spanish Inquisition. The Spanish tribunal began in 1478, near the end of the medieval period, and was a later institution with a distinct political role. Medieval inquisitorial courts could impose religious penalties, while secular authorities often carried out harsher punishments.