That policy held at bay in all things the pretensions of the Holy See, and looked with extreme suspicion on whatever might give the popes an excuse for interference with either the domestic policy or the foreign enterprises of the Signoria. Fairly orthodox, though not bigoted, Venice held aloof from the strife between Guelf and Ghibelline, and was not involved in the anathemas lavished upon Ezzelin da Romano. Venice, in fact, was the basis of operations in the crusade against him, and it was a Venetian who led the expedition up the Brenta which captured Padua. Yet the republic made no haste to join in the movement for the extermination of heresy so energetically pushed by Gregory IX. and his successors. The Constitutions of Frederic II. were never inscribed in its statute-books. In 1229 the official oath of the Doge Giacopo Tiepoli, which, as is customary, contains the criminal code of the day, embodies no allusion to heresy or its suppression, and the same is true of the criminal statute of 1232 published by the same doge.[281] It was about this time that the Inquisition was developed with all the aggressive energy of which Gregory IX. was capable, but it found no foothold in Venice. Yet the duty to punish heresy was at length recognized, though the civil authorities would abate no jot of their right to control the administration of justice in spiritual as well as in temporal matters. The official oath taken in 1249 by the Doge Marino Morosini contains a promise that certain upright and discreet and Catholic men shall be appointed, with the advice of the Council, to inquire after heretics. All heretics, moreover, who shall be delivered to the secular arm by the Archbishop of Grado or other bishops of the Venetian territories shall be duly burned, under the advice of the Council, or of a majority of its members. Thus a kind of secular Inquisition was established to search after heretics. The ancient jurisdiction of the episcopal courts was alone recognized, but the judgment of the bishops was subject to revision by the Council before the death-penalty could be inflicted.[282]