The origins of the doctorate in particular dates back to the ijazat attadris wa 'l-ifttd ("license to teach and issue legal opinions") in the medieval Islamic legal education system, which was equivalent to the Doctor of Laws qualification and was developed during the 9th century after the formation of the Madh'hab legal schools. To obtain a doctorate, a student "had to study in a guild school of law, usually four years for the basic undergraduate course" and at least ten years for a post-graduate course.