Abstract
This article examines how non-codified Shari'ah governing Islamic banking and finance agreements should be applied to ensure certainty and predictability of the applicable rulings. The significance of this topic stems from the fact that the multiplicity of schools of Islamic law or fiqh has given rise to concerns about the certainty of the applicable rules. Here we set out these concerns through the lens of English courts and argue that non-codified Shari'ah has the status of a law in Jordan regulating Islamic banking and finance agreements. It overrides legislation and excludes Statute Law that could invalidate agreements acceptable in Shari'ah. Further, the concepts of maslahah and istihsan are explained as bases for the selection of applicable Shari'ah rulings. This approach ensures certainty and is better than codifying rigid rules from Shari'ah that could impede the development of Islamic banking and finance.