IJMĀʿ. The Arabic term ijmaʿ, which means "agreement" or "consensus," becomes in Islamic jurisprudence the designation for one of the four sources of law posited by classical Sunnī theory, namely the consensus of the Muslim community. This consensus ranks as the third of the four sources, the first, second, and fourth of which are the Qurʾān, the sunnah (custom) of the prophet Muḥammad, and analogical reasoning (qiyās). For the majority of Sunnī legal theorists, the work of constructing legal rules is carried on by qualified scholars, called mujtahids, on behalf of the community as a whole. Whatever these scholars agree upon is therefore constitutive of the consensus of the community, and it is not necessary for them to take into account the views of an unqualified laity. The majority of theorists further hold that an authoritative consensus is...