Muslim countries that retain or adopt Sharia usually determine which parts of the Sharia are enforceable and codify (and thereby modernize) them. Unlike other Muslim countries, Saudi Arabia regards uncodified Sharia in its entirety as the law of the land and does not interfere with it. It is, therefore, unique not only when compared to Western systems, but also in comparison to other Muslim countries, and according to one source is the closest system in the modern world to the form of Sharia adopted at the advent of Islam.