This law, or rather the bull _Ad Extirpanda_, which contains it, was to be inscribed in perpetuity in all the local statute books. Any attempt to modify it was a crime, which condemned the offender to perpetual infamy, and a fine enforced by the ban. Moreover, each podestà, at the beginning and end of his term, was required to have this bull read in all places designated by the Bishop and the Inquisitors, and to erase from the statute books all laws to the contrary. At the same time, Innocent IV issued instructions to the Inquisitors of upper Italy, urging them to have this bull and the edicts of Frederic II inserted in the statutes of the various cities.[1] And to prevent mistakes being made as to which imperial edicts he wished enforced, he repeated these instructions in 1254, and inserted in one of his bulls the cruel laws of Frederic II, viz., the edict of Ravenna, _Commissis nobis_, which decreed the death of obdurate heretics; and the Sicilian law, _Inconsutilem tunicam_, which expressly decreed that such heretics be sent to the stake. [1] Cf. the bulls _Cum adversus, Tunc potissime, Ex Commissis nobis_, etc., in Eymeric, ibid., pp. 9-12. These decrees remained the law as long as the Inquisition lasted. The bull _Ad Extirpanda_ was, however, slightly modified from time to time. "In 1265, Clement IV again went over it, carefully making some changes, principally in adding the word 'Inquisitors' in passages where Innocent had only designated the Bishops and Friars, thus, showing that the Inquisition had, during the interval, established itself as the recognized instrumentality in the prosecution of heresy, and the next year he repeated Innocent's emphatic order to the Inquisitors to enforce the insertion of his legislation and that of his predecessors upon the statute books everywhere, with the free use of excommunication and interdict."[1] [1] Lea, op. cit., vol. i, p. 339. A little later, Nicholas IV, who during his short pontificate (1288-1292), greatly favored the Inquisition in its work, re-enacted the bulls of Innocent IV and Clement IV, and ordered the enforcement of the laws of Frederic II, lest, perchance, they might fall into desuetude.[1] [1] _Registers_, published by Langlois, no. 4253. It is therefore proved beyond question that the Church, in the person of the Popes, used every means at her disposal, especially excommunication, to compel the State to enforce the infliction of the death penalty upon heretics. This excommunication, moreover, was all the more dreaded, because, according to the canons, the one excommunicated, unless absolved front the censure, was regarded as a heretic himself within a year's time, and was liable therefore to the death penalty.[1] The princes of the day, therefore, had no other way of escaping this penalty, except by faithfully carrying out the sentence of the Church.