In reality, strange as it may seem, the Church itself in the West had little experience in dealing with large, organized heretical sects, and as a result had no procedure ready at hand to cope with them. This may be accounted for by the fact that the individual heretics that had gathered somewhat of a following in the past were clerics and could be dealt with by ecclesiastical censure: deprivation of benefices, removal from office, expulsion from the monastery. Other aberrations were academic and usually did not spread beyond the halls of academe. Albigensianism and Waldensianism were quite otherwise, both because of the direct challenge of their doctrine, and the increasingly large numbers involved. Confronted with the daily perversion of the faithful, individual bishops were concerned with their responsibility to safeguard the faith in their diocese.
Albert Shannon, The Medieval Inquisition (1991)