Interdict, in the Roman Catholic church, an ecclesiastical censure, or penalty forbidding public worship and the administration of the sacraments to certain persons or in certain places. Generally speaking, what the Roman Catholic church considers as the necessary rites of religion were not forbidden, such as baptism, confession, and extreme unction. Indeed, all the sacraments in most cases continued to be conferred privately, the solemn services alone being suspended. The canon law recites three kinds of interdict, local, personal, and mixed. The first directly affected the place, and indirectly its inhabitants, and them only while within its limits. The second affected the persons, who were interdicted the solemn services wherever they might be. The third combined both these effects. In the beginning interdicts were employed by all persons having episcopal jurisdiction, but in course of time their use was restricted to the Roman pontiffs. They were scarcely known until after the Carlovin-gian period, when the interdict became a powerful ecclesiastical weapon for restraining the violence of the feudal nobles.

However, one instance of its use occurred in 586, when Queen Fredegonda having caused Praetextatus, bishop of Rouen, to be slain in his own cathedral, Landowald, bishop of Bayeux, with the advice of the local clergy, commanded all the churches in the city to be closed and public services to cease till the instigators and perpetrators of the crime had been discovered. In the 10th century the popes began to have recourse to interdicts in their contests with sovereigns. In 997 Gregory V. laid all France under an interdict because King Robert had married his own cousin, and the king was abandoned by most of his court. The same penalty was inflicted upon the kingdom of England under Stephen (1147) by Eugenius III., under John (1208) by Innocent III., under Henry VIII. (1535) with little effect by Paul III., and under Elizabeth (1587) by Sixtus V. Adrian IV. laid Rome under an interdict for the purpose of driving out Arnold of Brescia. Gregory IX. made use of the same weapon in his quarrel with the emperor Frederick II.; and Paul V. in 1606 laid an interdict upon the republic of Venice in consequence of the passage of certain decrees relating to ecclesiastical matters. The government resisted the promulgation of the bull, and ordered the parochial clergy to continue their functions as usual.

From the time of the reformation, local interdicts became rare; personal interdicts, which are the severest forms of ecclesiastical censure, are still imposed.