It's not called Shari'a 'law' because Shari'a is a law. It's the law of Allah, divine guidelines and rulings in all aspects of life that is for all of mankind to follow.
But it must also be clearified that when people think of Shari'a they think of just the legal punishments, such as the punishment for illegal sexual acts, stealing, homosexuality etc but there is much more to Shari'a then this. It includes every single aspect of your life, such as how to pray, how to perform wudu (ablution) for prayer, where to face when performing prayer, how to fast, when to fast, how to treat your parents etc.
I will post some articles and videos in my next few posts insha'Allah to clearify this further.