Usman Raziallah Unho was the third caliph of Muslims. In the reign of Usman R.A the procedure of ijtihad was carried out exactly the same manner as that during the lifetime of Holy Prophet Muhammad (PBUH) and two prior caliphs :Abubakar R.A and Omer R.A. In order to solve a new problem ,first Quran was consulted, then Suunah(practices of Muhammad (PBUH) ,then the consensus of early two caliphs. Usman R.A would take guidance from Quran and Sunnah,On occasions where he would think that the particular problem has no prominent solution given in Quran and Sunnah ,he would try to take a logical and reasonable decision on the basis of rules and principles of Quran and Sunnah . Usman R.A used his scholarly consensus to escape Muslim Ummah from grave problems on many occasion. He fulfilled his duties as a caliph of Islam.
Muhammad Zubair, Mumtaz Khan. (2014) Methodology of Hazrat Uthman (r.a) in ijtehad:A research overview, Acta Islamica, Volume-02, Issue-1.