By prediction of Majlis as a legislatory organ and guardian council as a monitoring organ, it is imagined that securing legitimacy (necessary condition) and efficiency (sufficient condition) of the legislation is occurred simultaneously, but in considering to establishment of Expediency Council and confirmation of Majlis opinions in the matter of differences with guardian council observations the main legitimacy of in laws.The present analytical method in research in the first part, after introduction proposal of issue and reviewing of historical facts which leads to formation of expediency council, we will pay attention to concept of expedience in shi'ite jurisprudence Then on this basis it is focused on present ideas in showing of these in laws legal nature.
)