This work constitutes a critical analysis of classical and modern aspects of the concept of istihsan (juristic preference), an important principle in Islamic legal legislation throughout history. Although there has been many research works on the subject, it still requires further investigation on the role and nature of istihsan with regard to a combination of classical and modern approaches. Consisting of four chapters, the author begins by introducing some general principles of Islamic law, before discussing the history of istihsan during the time of the Prophet and his Companions. He also analyses the validity of istihsan as a source of law and discusses the differences among scholars on its method of implementation.