Islamic influence on the presumption of innocence:

The historian Marcel Boisard states in his journal “On the probable influence of Islam on western public and international law”, published in the International Journal of Middle East studies:

It was above all the very high ethical standard of Islamic law that impressed the medieval West and provoked the development of a more refined legal thinking. This aspect is undoubtedly the most durable merit of Muslim influence, as illustrated by the administration of justice. Until the Crusades, legal procedure in the West consisted of “God’s judgments” by boiling water or by duel, or by “ordeal” during which people were burnt with red-hot irons or boiling oil and, if they survived, declared “not guilty.” In contrast, we have only to quote the instructions given by Omar in the seventh century to the Muslim judges to show what a chasm separated the two conceptions: “Only decide on the basis of proof, be kind to the weak so that they can express themselves freely and without fear, deal on an equal footing with litigants by trying to reconcile them.”

From Islam’s beginnings the suspect was presumed innocent until it could be proved otherwise. It is certainly not a coincidence that Louis IX was the monarch who created the French legal administration by appointing “royal inquirers,” by instituting testimonial proof, and by permitting the recourse of “making a plea to the King.” The legislation he introduced marked a turning point in the history of law in Europe. Popular imagery was not mistaken on this point, since it is that above all which was remembered. Louis IX had frequented the philosophic theologians of his time; he had received St. Thomas Aquinas at his table. The influence of Islam was, however, even more direct. We can make this presumption since it was on his return from Palestine that the King undertook his major legal reforms. Joinville (Jean de Joinville, chronicler of St Louis) gives us fairly clear proof in his writings.