The consideration of custom as a structural benchmark of legal solutions alongside shar'i principles elucidates the strong links between political strategies, religious institutions and legal systems. More specifically, it provides unique insight into the creation of national religious identities through the exercise of state authority. Analysis of the legal concept of custom ('urf) within contemporary Saudi and Iranian legal systems uncovers the connection between the interpretation of religious texts and contextual atmosphere. In applying a legal anthropological method, this book considers the position of custom within Hanbali and Ja'fari jurisprudence as a legal source and compares the implementation procedure of legal systems with actual court cases from Iran and Saudi Arabia. Irrespective of whether there is a direct reference to custom, the interpretation and use of Islamic legal principles have a relatively close connection to the surrounding contextual environment. However, the extensive use of customary norms in the absence of legal sources or during the interpretation of legal texts are occasionally in excess of the permitted legal limits. The book compares the methodologies of scholars, diversity of legal opinions (fatwas) and court verdicts (ahkam) between the two countries by placing a particular emphasis upon the usage of custom, whether in the form of a legal principle with a semi-independent style or the form of a subsidiary source that is dependent upon various legal principles.