International audienceMongol law, the jasaq, haws provied the basis of a long tradition of studies which were inaugurated by Pétis le la Croix in 1710. He was the first to definine a list of precepts of the jasaq, but without taking consideration either the chronologie or their origin. Most subsequent scholars deling with the question revived the same vision of the jasaq. Debate focused on whether or not the Mongols possed a written code of laws. But, until now, little discussion has taken place concerning with the jasaq represented for the Mongols themselwes and how this Mongol « law » was percieved by medieval authors who, on the whole, confused the edits (jasaq) with customs (yosun). The paper examines the jasaq in its political and cult...