| The Prince and the Law, 1200-1600: Sovereignty and rights in the Western legal tradition K Pennington Univ of California Press, 1993 | 650* | 1993 |
| Pope and bishops K Pennington The papal monarchy in the twelfth and thirteenth centuries, Philadelphia, 1984 | 198* | 1984 |
| Popes and Bishops: The Papal Monarchy in the Twelfth and Thirteenth Centuries. K Pennington University of Pennsylvania Press, 1984 | 168 | 1984 |
| The History of Medieval Canon Law in the Classical Period, 1140-1234: From Gratian to the Decretals of Pope Gregory IX W Hartmann, K Pennington CUA Press, 2008 | 144 | 2008 |
| The History of Medieval Canon Law in the Classical Period, 1140-1234 W Hartmann, K Pennington, MH Hoeflich, JM Grabher | 144* | |
| Law, legislative authority, and theories of government, 1150-1300 K Pennington The Cambridge history of medieval political thought c, 350-1450, 1988 | 115 | 1988 |
| Bartolome de las Casas and the Tradition of Medieval Law KJ Pennington Church History 39 (2), 149-161, 1970 | 108 | 1970 |
| Innocent until proven guilty: The origins of a legal maxim K Pennington Jurist 63, 106, 2003 | 91 | 2003 |
| Due Process, Community, and the Prince in the Evolution of the Ordo iudiciarius K Pennington | 58 | 1999 |
| The History of Byzantine and Eastern Canon Law to 1500 W Hartmann, K Pennington CUA Press, 2012 | 52 | 2012 |
| The History of Byzantine and Eastern Canon Law to 1500 W Hartmann, K Pennington, S Wessel | 52* | |
| Learned Law, Droit savant, gelehrtes Recht: the tyranny of a concept K Pennington Syracuse J. Int'l L. & Com. 20, 205, 1994 | 51 | 1994 |
| The legal education of Pope Innocent III K Pennington | 51 | 1974 |
| The Biography of Gratian, the Father of Canon Law K Pennington Vill. L. Rev. 59, 679, 2014 | 45 | 2014 |
| Popes, Canonists, and Texts, 1150-1550 K Pennington Ashgate, 1993 | 43 | 1993 |
| The Decretists: The Italian School K Pennington, WP Müller Hartmann and Pennington, History of Medieval Canon Law, 121-173, 2008 | 42 | 2008 |
| “Pro peccatis patrum puniri”: A Moral and Legal Problem of the Inquisition K Pennington Church History 47 (2), 137-154, 1978 | 40 | 1978 |
| Lex naturalis and Ius naturale K Pennington Crossing Boundaries at Medieval Universities, 227-253, 2011 | 39 | 2011 |
| Pope Innocent III's views on church and state: a gloss to Per venerabilem K Pennington University of Pennsylvania Press, 1977 | 39 | 1977 |
| The rite for taking the Cross in the twelfth century K Pennington Traditio 30, 429-435, 1974 | 39 | 1974 |
