Although many use the terms “Shariah” and “Islamic law” interchangeably, they are not the same thing. Shariah is not a formal legal system. It refers to God’s law, sacred and unchangeable principles and values revealed in the Quran and the example (Sunnah) of Muhammad. Islamic law (fiqh) is the Muslim interpretation of those Shariah principles, the development of a vast body of laws or legal systems by jurists. While Shariah principles do not change, Islamic law is the product of human interpretations of Shariah in historical and social contexts and therefore can change in response to new challenges and circumstances. More here.