Welcome to Harry Potter Theory. Today we’re discussing Magical LAW. That’s right, just like the muggle society, witches and wizards are confined to behaving within the framework of law and order.
We saw a little bit of this in the films- like when Harry had a disciplinary hearing before the Wizengamot. In this instance, Harry had performed underage magic (a Patronus Charm) in order to ward off Dementors attacking him and his cousin Dudley.
"Disciplinary hearing of the twelfth of August, into offences committed under the Decree for the Reasonable Restriction of Underage Sorcery and the International Statute of Secrecy by Harry James Potter, resident at number four, Privet Drive, Little Whinging, Surrey.”
Fortunately for Harry, Dumbledore stepped in and protected him- which resulted in Harry walking away with no charges.
However, underage magic is just ONE ‘law’ in a wizarding society that actually has a lot more laws than you may have thought. Today we’re going to be uncovering them- at least, all of the ones we have information on.
I should also add that I won’t be conflating ‘Law’ in the sense of legislation with ‘Law’ in the sense of a set of principles or scientific axioms.
I.e. the ‘Law’ for underage magic is a piece of legislation prohibiting the use of underage magic and GAMP’S LAW is a set of scientific principles. 
Let’s dive in.