The daily life of Muslims is guided by
an elaborate code of laws worked out over the centuries, based first on the Qur» an, then on the traditions concerning the Prophet, then the consensus of the Islamic community, and finally in a limited area on individual interpretation.
Later in the Middle Ages, and particularly during the era
of the Hundred Years War, this canonical and theological conception
of just war was further
elaborated by incorporation
of ideas, customs, and practices from the chivalric
code and the experience
of war, from renewed attention to Roman
law, especially the jus gentium, and from the developing experience
of government.