I know a lot of you won't believe this. But trust me, I know what I'm talking about--knowing this stuff is part of my profession. This is not a scholarly forum, but if it were, I would happily provide plenty of bibliography. If anyone is interested, Bernard Weiss's "In Search of God's Law" is among the most authoritative books written by a Western scholar on this topic.
"Shariah" is God's Law: God's commandment's concerning human actions, which are categorized as: 1) obligatory 2) forbidden 3) recommended 4) disapproved 5) neutral.
Since God, in the Qur'an and the Sunna (Muhammad's deeds, sayings, and way of life), does not often explicitly state which actions belong to which category, it is left to humans to try to figure this out.
Human interpretations are called "fiqh," loosly translated as "law." They are attempts to figure out Shariah--but they are just attempts: they vary among different interpreters and in different times and places. So, "law" is not Shariah--it is an (imperfect) effort to understand Shariah. This makes for a very flexible legal code that can be altered and adapted according to historical circumstances.
Needless to say, there have been countless such interpretations. Anyone who says there is such a thing as "the Shariah law" is wrong. Not to mention the fact that Shariah and Law ("fiqh"
are two very different things.
True, idiot ISIS types and other so-called "Islamists" think there is such a thing as THE Shariah Law. That does not make them right--and in this area, as in pretty much everything concerning the classical formulations of their religious tradition, they know nothing.