<論文>スンナ派イスラーム法学における既判力論争の展開 --マムルーク朝期を中心に--

Abstract

This study discusses the idea of the res judicata in classical Islamic jurisprudence and the historical background for the debate on the subject. The res judicata (Latin: “matter adjudicated”) doctrine is of Roman origin and is designed to preclude relitigation of a given matter once the question has been decided on its merits, thus guaranteeing legal stability and social harmony. In his monograph on the subject in the context of Islamic law, E. Tyan reports that no such doctrine has been elaborated by Muslim jurists, who consider that the reversal of a qaḍī’s ruling generally permissible. Contrary to his contention, however, we note that court rulings may not be annulled according to an established principle of Islamic jurisprudence. Moreover, it is exactly in relation to the question of “ruling on effect (ḥukm bi-al-mūjab)” as opposed to “ruling on validity (ḥukm bi-al-ṣiḥḥa)” that Muslim jurists do discuss cases of res judicata, i. e., when and to what extent a ruling generates the final and binding force. The method of ruling on effect was introduced as a remedy for plaintiffs who cannot completely establish the validity of their transactions or, for qaḍīs, as an expedient for avoiding the annulment of their rulings. In the Mamluk period, when the four Sunni schools of law were in conflict with one another, many cases of denial of the authority of rulings issued by the qaḍīs of other schools appeared; hence, against the backdrop of these disputes regarding res judicata, a series of treatises were written in defence of this method of ruling by precedent. I will investigate the five important works in this context that were authored by Taqī al-Dīn al-Subkī (d. 756/1355), who was a pioneer in the development of the subject and his two Shāfiʻīte followers as well as Ibn Qutlūbghā (d. 879/1474) and his contemporary Ibn al-Ghars (d. 894/1489) from among the Ḥafanīs.