Pope Innocent was one of the most powerful and influential of the medieval popes. He exerted a wide influence over the Christian states of Europe, claiming supremacy over all of Europe's kings. He was central in supporting the Catholic Church's reforms of ecclesiastical affairs through his decretals and the Fourth Lateran Council. This resulted in a considerable refinement of Western canon law. He is furthermore notable for using interdict and other censures to compel princes to obey his decisions, although these measures were not uniformly successful.