The laws of magic only applies to those who only use magic correct?
That's going to depend on you and your group and how you want to interpret the laws.
To me, there's 2 sides to the laws.
1) The Wardens. If they suspect you broke a law, they will act. It doesn't matter much if you DID break the law, if they suspect you did, you are in trouble. You can probably get away if you can prove innocence or some technicality, but first they will hunt you down.
2) The mental impact. Even if the Wardens don't know what you did or you are out of their jurisdiction (by using sponsored magic, for example), using magic in a certain way will probably have an impact on you, no matter where it comes from. You are wielding the power, you choose what the power is supposed to do, you deem right what the power does, twisting the power this way changes you.
There are ways around it, as well. Your sponsor could insulate you from the effect, for example, but that will come back to bite you in another way for sure.
When you do a spell that can break the law, either or both of those could apply. A Warden might want to talk to you for a spell that didn't affect you mentally, or a spell might affect you that doesn't even make it on the Warden's radar. Or both.
When it comes to using it in play, the important part is always: choose what you think will be fun. Just because someone broke the law doesn't necessarily mean they need to take the lawbreaker stunt, for example. There are other ways to deal with this, especially since the Lawbreaker can often mean the NPCness of a player character.