Causa and opinion evidence: the Roman-canonical origins of the prohibition of opinion evidence in the common law

Abstract

Since Bentham’s critical analysis, the historical narrative would appear to be settled once and for all: the English law of evidence is a recent creation of the common law and should be understood as a reaction against its particular procedural features. What if one questions that postulate and is prepared to accept the opposite theory of ancient origins, which would have been contemporary to the legal re-invention of the Roman-canoncal ius commune on the Continent? In such an alternative approach, one may find that the sources reveal correspondences between the two legal traditions, perhaps even an influence from one tradition on the other, and also functional adjustments of the imported institutions and mechanisms. The point may be illustrated through the law of testimonial evidence, more precisely two of its features. The argument may start with a very common case from 1349. An important development of the Roman-canonical law, which greatly affected legal practice on the Continent, insisted on the requirement that witnesses should found the statement of their knowledge they made before the court on the use of their own senses. A similar rule exists in English law, the prohibition of “opinion evidence”. It is possible to identify a Medieval origin to that principle and to form the hypothesis that it was inspired by canon law. The English system was nevertheless original and its effects were specific to the way the common law operates. In any event, the relationship between witnesses and the jury makes it possible to understand the specificities of the English rules. However, the role of the jury cannot by itself allow the historian to explain why and how those rules were adopted, nor, therefore, the law of evidence was developed.