One of the anomalies of the Middle Ages was that there were practically no prisons for the containment of those convicted of serious crimes. What prisons there were had for their purpose the retention of prisoners prior, merely, to their trials. The great legal historian Frederick W. Maitland has noted the reason for this situation, succinctly: “The one punishment that can easily be inflicted by a state which has no apparatus of prisons and penitentiaries is death.” Death and mutilation were the accepted punishments for convicted felons in the legal codes of the Middle Ages.
Against this peremptory, harsh code, the Church put forth its traditional abhorrence of bloodshed and exercised its influence to turn secular legislation away from blood sanctions. She introduced the idea of atonement, that the sinner, given time, would turn from his evil ways and amend his life – and cautioned that this time of grace should not be abruptly cut short by an immediate death sentence. There was a long list of felonies for which the only punishment was death or mutilation. However under the impetus of the Church other means found their way into secular legislation.
Impelled then to evolve a more humane method for dealing with serious delinquencies, the Church recommended imprisonment, whereby the convicted heretic might have time to meditate on his errors and might hopefully return to the Catholic Faith. At the same time she protected the faithful from being corrupted by heretical doctrine. Hence, the Church considered imprisonment a medicinal penalty, not a vindictive one.
Albert Shannon, The Medieval Inquisition (1991)