Sources of Law, 4: Canon & European Common Law

Canon Law: From their early days Christian churches considered the Bible as containing a body of laws regulating many aspects of life, and soon the decisions of church councils were also accorded considerable authority. After the conversion of the Emperor Constantine ca. 312 CE/AD, the Church became state-supported and soon thereafter state-mandated. In the ensuing period of close partnership between the late Roman state and church, ecclesiastical law drew increasingly on such sources as the decisions of church councils, the writings of eminent church leaders (like Augustine of Hippo), and many ideas and principles drawn from Roman Law. With the fall of the western half of the Roman Empire ca. 500 CE/AD, the western or Roman Catholic Church also accorded authority to the decrees issued by the Pope (or bishop of Rome). By the mid-twelfth century, with the rediscovery of the texts of the Body of Civil Law, canon law began to incorporate more systematically than it had done before many elements of Roman Law. At this time canon law became the subject of formal academic study in the emerging universities.


European ‘Common Law’ (ius commune): After the re-discovery of Justinian’s Body of Civil Law in ca. 1100, Roman Law also began to be studied and taught as an academic discipline in the universities (first in Bologna, Italy). But this was a neo-Roman Law that was studied and applied in a very different context from that of ancient Rome. For example, there was much mutual influence between this new Roman law and canon law, which together provided the basis for university-level legal education. From the interaction between these two types of ‘learned law’ a new synthesis emerged, which is sometimes called Romano-canonical law, or the ius commune (European ‘Common Law’). It was used throughout western Europe down to the nineteenth century. From the start this European Common Law also influenced, and was influenced by, the secular systems of formal law that were at this time developing in most European regions and countries.


The “Two Laws:” The above two legal traditions were closely interrelated, especially insofar as they concerned secular (or nonreligious) matters. Many university-trained lawyers who studied both of these types of law became known as experts of “the two laws.” Although the selections below are drawn from canon law, they were equally a part of the European Common Law. The Romano-canonical synthesis of the ius commune was especially influential in such areas of the law as contracts, property, and legal procedure, all of which depended heavily on Roman legal ideas, definitions, and categories. Perhaps the ius commune‘s greatest contribution was in developing explicit and detailed norms of due process.


  1. Due Process: “No one may sentence and no law may condemn someone who is absent” (Gratian, Decretum, ca. 1140, C.3 q.9 c.4). “The defendant shall be summoned properly and before his own judge… He must be permitted to have legitimate delays. The accusation must be formally presented in writing. Legitimate witnesses must be produced. A decision may be rendered only after someone has been convicted or confessed. The decision must be in writing” (Stephen of Tournai, Commentary on Gratian’s Dectretum, ca. 1165, at C.2 q.1).

  2. The Presumption of Innocence: “A person is presumed innocent until proven guilty (quilibet presumitur innocens nisi probetur nocens)” (Johannes Monachus, Gloss on Pope Boniface VIII’s Decretal Rem non novam (1303), ca. 1310). After first being coined by the above canon lawyer in the early fourteenth century, this expression or maxim was widely adopted by jurists and thinkers throughout the Western world. The maxim acquired broader recognition by the general public when a statement very close to the above was incorporated as article 9 of the French Declaration of the Rights of Man and Citizen of 1789. A very similar statement now also figures as article 11 of the U.N.’s Declaration of Human Rights of 1948. Surprisingly to modern Americans who have all heard the statement, “innocent until proven guilty,” no such expression is found in early Anglo-American constitutional texts, such as the Magna Carta, the English Bill of Rights, the U.S. Declaration of Independence, or the U.S. Constitution. Nor has it ever been incorporated into the U.S. Constitution. Nonetheless, by the early nineteenth century a version of this maxim was also familiar in the U.S. It finally became a formal part of U.S. law through a Supreme Court decision of 1894, which affirmed the validity of the expression, “the law presumes that persons charged with crime are innocent until they are proven by competent evidence to be guilty” (Coffin vs. U.S., 156 U.S. 432, 432-463).

  3. The Origin of Slavery (and Inequality): “God did not intend that his rational creature, who was made in his image, should have dominion over anything but the irrational creation— not man over man, but man over the beasts. And hence the righteous men in primitive times were made shepherds of cattle rather than kings of men. For it is with justice, we believe, that the condition of slavery is the result of sin. And this is why we do not find the word slave in any part of Scripture until righteous Noah branded the sin of his son with this name [Genesis 9:20-27]. It is a name, therefore, introduced by sin and not by nature. The origin of the Latin word for slave [servus] is supposed to be found in the circumstance that those who by the law of war were liable to be killed were sometimes preserved by their victors, and were hence called servants [servi]. And these circumstances could never have arisen save through sin. The prime cause, then, of slavery is sin, which brings man under the dominion of his fellow, and which does not happen save by the judgment of God. But by nature, as God first created us, no one is the slave either of man or of sin. This servitude is, however, penal, and is appointed. And therefore the apostle admonishes slaves to be subject to their masters, and to serve them heartily and with good-will [Ephesians 6:5], so that, if they cannot be freed by their masters, they may themselves make their slavery in some sort free, by serving not in crafty fear, but in faithful love, until all unrighteousness pass away, and all principality and every human power be brought to nothing, and God be all in all” (Augustine of Hippo, City of God, ca. 430 CE, ch. 19.15).

    Further Reading:

  • Bellomo, Manlio. The Common Legal Past of Europe, 1000-1800.  Washington, D.C.: Catholic University of America Press, 1995.
  • Brundage, James A., Medieval Canon Law. New York: Longman, 1995.
  • Pennington, Kenneth, The Prince and the Law, 1200-1600. Berkeley: University of California Press, 1993.
  • Pennington, Kenneth. “Learned Law…,” 1994, available in an updated form on his website, here.
  • Pennington, Kenneth. “Innocent Until Proven Guilty: The Origins of a Legal Maxim,” 2005, available on his website, here.