The word fatwa is derived from the root fata, which includes in its Semanic fields the meaning youth, newness, clarification, or explanation. These connotations have survived in its various definitions. Its development as a technical term originated from the Koran, where the word is used in two verbal forms meaning asking for a definitive answer and giving a definitive answer (4:127, 176). The concept of fatwa in early Islam developed in the framework of a question and answer process of communicating information about Islam. The technical usage of the term was further refined after the compilation of legal literature by different schools, and it thus came to mean a legal opinion or legal ruling.

In Ismailism, the Imam is a sole authority. His guidance and order are the legal ruling, therefore, no person is authorized to issue fatwa on any religion matter. One can however make his judgment in view of the guidances of the Imam, but his judgment cannot be regarded conclusively.

Devin J. Steward writes in Islamic Legal Orthodoxy (Salt Lake, 1998, p. 179) that, "It is the Caliph (Imam) who has ultimate authority on religious matters. Others, like al-Qadi al-Numan himself, are entitled to issue legal opinions and hand down verdicts, but only through the permission of the Caliph (Imam); their authority is derivative and dependent."