An interpretation of Gratian's Decretum, based on the discovery of a shorter, original version.

List of illustrations; List of tables; Preface; List of abbreviations and Conspectus siglorum; 1. Gratian and the Decretum; 2. Heresy and excommunication: Causa 24; 3. Obedience or contempt: Causa 11, Questio 3; 4. The two recensions of the Decretum; 5. Gratian and Roman law; 6. The men behind the Decretum; Conclusion: medieval law and the Decretum; Appendix: the contents of the first recension of Gratian's Decretum; Bibliography; Index of cited passages in Gratian's Decretum; Index of papal letters; General index.