Since the beginning, legal theory has concerned itself with the establishment of principles and precepts that govern the procedure of legal interpretation, from the initial stages of the judicial reasoning down to the promulgation of ruling and their implementation, Islam is a total way of life. Muslims are obliged to abide by the rules of Allah in every aspect of their lives, always and wherever they live. However, the actual rules of Allah as given in the Qur’an and the sunna are limited. The Qur’an contains only six hundred verses directly related to laws, and there are approximately two thousand hadiths. The function of interpretation is to discover the intention of the Lawmaker of the matter, therefore, interpretat primarily concerned with the discovery of that which is rot self-evident the objective of interpretation is to ascertain the intention c the Lawmaker with regard to what has been left unexpressed as a matter of necessary interference from the surrounding circumstances. Sometimes, the textual sources did not provide detailed guidelines in which to derive the law, and then the role of interpretation is important to determine the law. In Islamic law the role of Ijtihad undoubtedly important in order to meet new problems. But some of the Jurist contended that the role of Ijtihad had ended and we have to follow the rule that has been stated. An explanation given to this trend is that a point had been reached at which all essential question of law had been thoroughly discussed and further deliberation was deemed unnecessary. In Common law, man-made law and legislation are related to one another within a philosophy of law. Parliament makes law and it is the duty of the courts to give effect to them if properly enacted. While courts may rule that a particular statute or section is invalid for various reasons such as unconstitutionality, they cannot say, "We shall change this Act because it is not appropriate". That function belongs to Parliament (Wu Min Aun 1990: 120). So as in Islamic law, the Lawmaker is Allah S.w.t and the sacred text (Quran) is legislated due to His intention whereas Sunnah of the Prophet Muhammad is enacted due to the Prophet's intention. Therefore, Ulama of Usul Fiqh, in making any Ijtihad, they are du y bound to be guided by Quran and Sunnah.