Dude, chill. There's nothing in the rules that backs up either interpretation. Fate is a pretty freeform system, incase you're not familiar with it and its design mechanics. And, like anything, flavor and mechanics are somewhat mutable.
It's a free form system. You can play it however you want. However, the rules do NOT distinguish between mortal or non-mortal casters, sponsored or non-sponsored magic as far as the Laws of Magic are concerned. The Laws of Magic are merely written to apply to the PCs, with zero mention of the sort of magic the PC has or even whether the PC is human or not.
I am NOT say one has to stick to RAW on this. I am saying the RAW, as best I read it, says the Laws of Magic (and the Lawbreaker consequence for breaking them) apply to PCs of any origin whether they use sponsored magic or not. Again, one can play this however one wants in a game, and I only bring this up because it is ideally important to know what RAW is so you know when you are stepping away from it.
I did reread the section on the Laws of Magic again, btw. Nowhere does it say that the laws only apply to a mortal caster. The only place it discusses human vs. inhuman casters (which is different than mortal vs. non-mortal for what it is worth), is in regards to targets of spells (like Toot Toot). Throughout the whole section, it is pretty clear the view is that the Laws, as a rule of creation (in universe) apply to all players. I believe they even talk about the important of the laws with regards to given muggles their own distinct edge with regards to PCs and magic, and that sort of principle would apply to any player (but admittedly it is purely one of game mechanics).
The above is why I bring up positive refresh as a decent baseline.
We see very few guys with sponsored magic in the lore who don't have mortal magic (by the way, I refer to text as the novels and rules as the game books, which I think caused some...misinterpretation on your part). A good example is that we don't see the former Winter Knight with Lawbreakers in OW. The only ones we see with Lawbreakers also have mortal magic. Oh, and Mavra's entry doesn't say anything about Lawbreaker despite her having some pretty dark magic (so dark Harry comments upon it). And there's a whole paragraph talking about the ambiguity of the "positive refresh rule" and how its only "one way" to interpret things.
The former Winter Knight doesn't need to have Lawbreaker. He's an NPC. NPCs very clearly do not need to follow the rules that PCs do. An NPC only needs a given ability if it is significant enough for them to have. If they don't feel the former Winter Knight's lawbreaking is meaningful enough, then there's no need to write him up with this. There are tons of places where they talk about how NPCs can break the rules in general both in the books and out. The same is true, of course, with Mavra. It is very sensible for a GM or a game designer to decide an NPC is more interesting with refresh spent elsewhere.
I'm not pretending anything, so stop being so offensive. The rules talk about "true black magic." Oh, and the series of stickies on YS236:
First, I'm not being offensive, so calm down. I'm neither being nice nor mean. Second, again, those sidebars are clearly talking about the Laws of Magic as enforced by Wardens, not the Laws of Magic as physical laws of the Universe. The two things are distinctly different in the rules even if they are both referred to as "The Laws of Magic".
Not arguing about mechanics. The GM can use whatever they want to represent their vision however they feel it should be. That's not really a great argument for how it should be always, and isn't really applicable to the OP.
Well, that's why I said positive refresh is a good principle to go by, generally. Note that the GM determines what enemies have positive refresh and which ones don't. Generally, it seems like anything that isn't human will have negative refresh, though exceptions certainly exist (like angels and even the rare other creature).
See InFerrum's sticky. GM Fiat can do whatever, but the rules say mortal spellcasters.
The rules say mortal casters with regards to Warden enforcement, not with regards to reality sticking you with Lawbreaker. The rules also explicitly say these two things are different.
Belief is part of the equation, however if you read some of what Jim has said about the laws you realize that these are actual physical laws. Laws of the universe if you will. When you use your magic to change the universe in these ways it changes you. Physically (or metaphysically). If you accidentally kill someone with magic it doesn't matter if you believed you had the right to do it or not. Someone's dead and you used your innermost being to do it. Lawbreaker.
The weapon definitely matters too. This doesn't happen with a gun or a knife, even if you believe you have the right to take a life, no lawbreaker. This only happens with magic. The way I see it sponsored magic isn't that sacred part of you, thus it doesn't work the same.
Agreed. I have read what Jim has said.
I can agree that there's definitely evidence to support either side. This is the way I choose to view it. There's intentionally some leeway in the text so that each table can decide what kind of game they want to play. Do you want to play a game where the laws are brutal and it's all too easy to slip up and wind up in a dark place? Great, do that. Do you want to play a fast and loose action game where everything explodes and it doesn't matter at all? Have fun.
I think we can all agree the rules pretty clearly say there are the Rules of Reality Laws of Magic and the Rules of the Council Laws of Magic. The latter only applies to mortal casters, no question. Reality punches anyone with free will in the face, but this is a term that cannot be properly defined. However, any player by definition of the system has free will, so he should get hit in the face. Note that despite the capacity to play non-humans in the system, the rules on breaking laws always says "players this" and "players that." It doesn't say "humans", "mortals", or the like, and is all about players. The only exception to this is when talking about the Council enforcing their own consequences to law breaking. To me this is pretty clear.
As a random side note, this is a really unpopular opinion but I've always thought that the way we see soulfire today is only because it's viewed through a wizard's bias. Why wouldn't someone be able to directly access the fires of creation themselves (I.E. not their soul, but the source of souls) and manipulate them in any number of different ways (I.E. not fire or force, like a certain someone). Then again the agenda of the sponsor with soulfire is such that I would think that it would be tough to break a lot of the laws anyway.
There are of course multiple ways you could go about it. In the game it seems pretty clear Soulfire uses up your own soulstuff, as opposed to you being given soulstuff from someone else. I suppose one way you could go is use whatever makes for a more interesting debt system.
Anyhow, regarding the OP, here's how I'd go with it.
You are a vamp wizard using your vampire powers to kill someone. Break any laws? What about the same vamp using wizardry to kill someone
Using Vampire powers? No. Using magic? If you are a PC, you get Lawbreaker. In the latter case, the Council will not come after you for breaking the law per se (e.g. if they come after you it isn't because they are being cops, more like an act of war or the like).
You've made a thrall with your natural powers. Now you use wizardry to do some specific tinkering. Do they have enough mind left to count for the mental law?
I'd say if they still have any sense of self or mind, then screwing around with their brain gets you Lawbreaker. If you get them to the point where they are no better than an animal, then you wouldn't.
Can you use wizardry to feed? Say using magic to induce the appropriate emotion, or just to rip out psychic energy for a white court. Does using magic affect your Hunger?
You could certainly use Wizardry to help yourself out and create emotions to feed on.
Hmm, you could even probably make a Thaumaturgic ritual to feed off of a given emotion in an area. That actual might be a good way to handle things. Why incite an emotion if you make a big ritual and feed off all the stray lust in an apartment building or something? You don't have to even adjust anyone's emotions this way, I'd say. Great tool for the Ethical White Court Vampire, I think, but it only works for wizards, unfortunately. Anyhow, no Lawbreaking is inherent here, though inciting an emotion, if you go that route, is on the edge (but it isn't making a thrall).