Some legal specialists rise to greater prominence because of their erudition, earning the title mujtahid (pronounced MUJtahid, “one who exercises independent investigation” of the sacred sources). In Sunni tradition, the “door of independent investigation” closed by the year 900, making further bold scholarship of this level unnecessary. According to that classical view, the founders of the four major Sunni schools of legal theory were the last mujtahids. But in Shi’a tradition, the highest ranking ayatollahs continue to exercise the authority of mujtahids.

In both traditions, it is up to scholars to offer rulings on controversial or contemporary issues. If a new ethical and legal question arises—a question of artificial life support or some other thorny biomedical matter, for example—a legal scholar would search the relevant sources to determine whether the Qur’an or Hadith might shed light on the precise issue at hand. If the scholar found only vague parallels that offer insufficient evidence to make a firm ruling on the new problem, he would then study further to see whether in the actual practice of Muslim communities there was an approach that might solve the problem. If the problem is too new to have any kind of useful history, the scholar might appeal to reasoning by analogy, looking for a “link” between ancient sources and practice and the new problem. Ancient sources may say nothing about artificial life support, but they have much to say about the nature of human life and about human authority to intervene.

On the basis of his research, the scholar might then issue a legal advisory called a fatwa. In that statement he would indicate to which of five ethico-legal categories the proposed course of action belonged: forbidden, discouraged, neutral, recommended, or required. Acting upon the advisory, the parties to the case might then choose to bring the matter before a religious judge called a qadi (pronounced KAAdee), himself authorized as a mufti. to adjudicate the matter. The outcome of all this study and interpretation is called Shari’a (pronounced shaREE’ah), the divinely revealed law or way of life prescribed for all Muslims.