Of the sixty-two provisions in the Magna Carta of 1215 only four have survived on the statute books today. One of these is the celebrated article 39 with its sibling article 52, which have become the fount of inspiration for the doctrine of due process that has received great attention in Anglo-American law. In this chapter, however, I shall leave to the expertise of the lawyers the subsequent development of due process downstream from Magna Carta where it evolved into trial by jury. As a medieval historian I shall limit myself to exploring its sources upstream chiefly in three streams, flowing from English law, canon law and the personal contributions of Archbishop Stephen Langton. This exploration contains little that will surprise experts familiar with the subject but will serve my particular purpose to highlight the contributions of Langton. Article 39 of Magna Carta states:

Article 52 applies the principle to the immediate situation:

The article then proceeds to apply the remedy to the disseisins of Kings Henry II and Richard as well and to entrust its ultimate enforcement to the judgment of the twenty-five barons as instituted by the barons in Magna Carta (article 61).

Due process may be defined as ‘the course of legal proceedings established by the legal system … to protect individual rights’. As defined here, the principle of due process is, in fact, a commonplace in jurisprudence, perhaps even a tautology, that is, the confusion of cause and effect.