Fatwas are based on the question and answer process found in the Quran, which seeks to enlighten on theological and philosophical issues, hadith, legal theory, duties, and the Sharia law.
The 16th century Ottoman Shaykhul Islam Ebussud Effendi issued a series of fatwas excommunicating Twelver Shi'ites as kuffar (disbelievers).
[5] He also proclaimed the legal verdict calling for the killing of the Kizilbash; which was implemented by Ottoman authorities to suppress Shi'ism throughout the empire.
[6][7] Declaring the Qizilbash as disbelievers and calling for their executions, Ebussud states: "These outrageous people became unbelievers as they scorned the Holy Qurʾan, the noble shariʿa, and the religion of Islam, disdained and killed scholars on account of their knowledge, [and] considered their immoral cursed leader god and prostrated before him.
[They] considered permissible many religiously forbidden acts whose prohibition has been established by definite scriptural sources, and cursed Abu Bakr and ʿUmar (the first two caliphs after Muhammad’s death), may God be satisfied with them.
"[30] This is demonstrated in the case of some Sunni fatwas issued in Pakistan, which were considered as defensive materials created for the purpose of defending the faith from the Shia.
[31] In 2004, both Sunni and Shia scholars released the so-called 2004 Amman Message, which established some form of standards to prevent or at least discredit and counter renegade interpretations such as those made by Osama bin Laden and Abu Bakr al-Baghdadi.
[32] This initiative outlined who are qualified to issue fatwas or legal opinions, promoting a more conservative framework over progressive interpretations.