: Al-Bid‘ah versus al-Mashlahah al-Mursalah and al-Istihsân: Al-Syâthibî's Legal Framework. This paper discusses with the juridical basis of Abû Ishâq al-Shâthibi's (d. 790/1388) argument against those who considered al-mashlahah al-mursalah (public interest) and al-istihsân (juristic preference) to be forms of innovation. The present discussion will examine the efficacy of al-Syâthibî's distinction between al-bid‘ah (innovation), which is foreign and even contradictory to the shariah and the validity of the legal principles of al-mashlahah al-mursalah and al-istihsân as subsidiary, yet valid sources of law under the Quran, the Sunnah, ijmâ', and qiyâs (ratio legis). In addition, it will be shown how al-Syâthibî's epistemological reliance on legal theory distinguished him from jurists who shared quite different views on the same matter. In the concluding remarks, the relevance of this theory with contemporary Muslim society with respect to pursuing legal practices is underlined.