A fatwa (Arabic: فتوى; plural fatāwā فتاوى) is a legal opinion on a point of Islamic law that a Mujtahid, a qualified jurist, can give. A Mujtahid derives fatāwā by referring to sources of Islamic law (the Quran, the sunnah, ijma’ (consensus), and ‘aql (the intellect)) and through exercising the methodology of ijtihad (juristic interpretation).
Fatāwā are considered universally applicable religious laws.
Fatāwā are generally issued in response to a question, whether it be on ritual, social, or political matters. The origin of the fatwa can be traced back to the Quran where Allah (s) instructed the Prophet (s) on how to address questions from the community in the pattern, “And when they ask you concerning… say…” Following the fatwa is obeying God’s laws. Not following the fatwa would be a rejection and disobedience of God’s laws.
In Shia Islam, fatāwā are considered binding, meaning that one must follow the fatāwā issued by the A’lam Mujtahid that they follow. According to Ayatullah Sistani, if a Mujtahid gives a fatwa on some matter, he and his followers cannot obey the fatwa of another Mujtahid. However, if one’s Mujtahid does not give a fatwa on a particular matter, then they may act on the fatwa of another Mujtahid who is permissible to follow.
References
As-Seestani, A. (2017). Islamic laws: According to the fatwas of His Eminence al-Sayyid Ali al-Husayni al-Sistani(M. A. Ismail, Trans.). The World Federation of KSIMC.
Tehrani, M. H. (2006). Faith and reason: A compendium of fifty questions and answers related to Islamic theology, jurisprudence and other themes(A., Trans.). Stanmore: Islamic Education Board of the World Federation of KSIMC.