My advice on this is a White Council "Lemon Test" for characters like this that skate the Laws of Magic/sponsorship thing.
If your proposed character falls under either of these rules then the Laws of Magic apply to that character:
1. Is the magic/power being used Mortal in origin?
Is it his own magic or is it someone else's?
The White Council only has purview over Mortal practioners of magic and the Laws of magic only apply to Mortal practioners because they represesnt acts that corrupt because Magic reflects its owner. If the magic isn't a Mortal's, if it comes from somewhere else, the user is just a channel and it comes from another source.
If it's someone else magic then the character is off the hook.
2. Is the purpose of the character to get around the Laws of Magic for the Player's personal amusement?
Context is everything. The Lawbreaker Stunts in the game and in the setting itself represent corruption. A person who kills mortals with magic is a big deal, so something or someone has to determine its morality for a character.
If the PC is meant to be someone who isn't a Wizard, but still has some things in place to control his/her actions then that can be dealt with. An Emissary of Power has a patron who dictates the limits of what that character can do. With that Patron under GM control then the Laws of Magic needn't be dealt with necessarily because if a PC melts down a bus full of nuns then the PC's patron will have words with that PC or cut him/her off and let the Mortal Authorities deal with him. The Player of that PC probably wants to play that character because he has power but isn't a Wizard so there really isn't a problem.
A problem exists if a Player wants to play a Character not bound by the Laws of Magic so he/she can get away with what is against the rules. If the PC exists solely so the Player can Kill, Enthrall, Raise armies of the Dead, etc then that PC needs the Laws of magic because the Character only exists for the Player to vent and do things that are against the rules.
"I want to kill humans!"
"I want to Rape people's minds!"
"I want to make people my personal puppets!"
"I want to Make the Army of Darkness!"
"I want to turn people into sheep!"
"I want to F@*$ around with Time!"
"I want an Outsider to be my B@($!"
If your player says any of these things with great glee, please consider no allowing their character that lets them do all that and maybe get them psychological help if they are serious.