Study area restriction of this article has a starting point from the three scientific grounding. They are ontology grounding which is related to the object of study, epistemology grounding which deals with the methods used in the study, and axiology grounding which deals with the usability or the significance of the study. The object of study in this article is interpretation of radicalism doctrine against Islamic law, it focused on three issues; they are the law interpretation of tagyir al-munkar, the law interpretation of jihad fi sabilillah, and the law interpretation of the Republic of Indonesia. The approach method used for the analysis are: (1) political approach; (2) statutory approach; (3) the analytical approach. Its study material is normative material; with the study technique of document analytical is descriptive analysis (explanatory). The framework of the theory that being used, in the grand landscape theory using the theory of ijtihad, in middle of the theory using the theory of law and society and on the plains of applied theory using the theory of the judicial system of the Islamic Shari’ah. The significance of this study is to find interpretation irregularities of Islamic law by the doctrine of radicalism and steps in coaching or prevention.