Almost all the legislation significant in establishing the medieval inquisition against heresy was created in the 130 years between 1184 and about 1320, a period which also saw major developments in thinking about canon and civil law, and about public justice in general. This chapter provides an overview of how the framework of inquisition evolved, with particular emphasis on it as a partnership activity. The papal inquisitor was not the only entity in Italy to have responsibilities for combating heresy: others had such duties before the inquisition took shape, and continued to exercise powers of their own after it was established. Although over the century of this book (1250–1350), the papal inquisition's role was greatly enlarged and entrenched vis-à-vis ecclesiastical and secular partners, the period should not, in Italy at least, be seen in terms of the inquisitor emerging supreme. The organisational structure formalised by Innocent IV in the early 1250s, and renewed by his successors, meant inquisitors continued to need support from both bishops and civic authorities, who also continued to exercise their own independent roles. The exact balance of power between the three parties shifted from place to place, and time to time, not only according to politics and strength of personality, but also the changing geography of heresy itself.

Early efforts against heresy

During the second half of the twelfth century, the Church struggled to find effective ways to combat the two major heresies, of the Cathars and Waldensians, which had taken firm root both in southern France and across north and central Italy. Bishops had responsibility for the spiritual health of their flock, but even when inclined to be active against heresy, they found it increasingly difficult to fulfil this element of their duties in a coherent way. There were a number of reasons for this, some specific to Italy. As Lambert has noted, there was an absence of established procedure, which left bishops uncertain where to turn when heresy was suspected. In both France and Italy there was widespread sympathy for Church reform, reflected in movements like that of the Humiliati. This easily morphed both into public tolerance of the anticlerical aspects of different heresies, and into heresy itself.