Usulis are the majority
Twelver Shi'a Muslim group. They differ from their now much smaller rival
Akhbari group in favoring the use of
ijtihad (i.e., reasoning) in the creation of new rules of
fiqh; in assessing
hadith to exclude traditions they believe unreliable; and in considering it obligatory to obey a
mujtahid when seeking to determine Islamically correct behavior.