First off, DFRPG is full of "the group should agree" (YS92), "keep in mind the intended play style" (YS31), "make sure your players are okay this" (YS338), "make sure you're on the same page as your players" (341), and "when in doubt, talk it through with your group" (YS99).
In many places throughout this book, the phrase “the GM decides” is often used interchangeably with “the group decides” regarding some of these issues, because it emphatically isn’t the GM’s job to run a dictatorship—every player should always be allowed the chance to have a say in those instances. The GM should act as more of a moderator, synthesizing the group’s input with her own in order to reach a final decision. [YS306]
But I'm going to focus on the Lawbreaker thing, because that's a lot more quotable, rather than an obvious system philosophy.
A concession has to pass muster with the group before it is accepted [YS 206]
This is framed in the context of a concession not being too lenient; it must "represent a clear and decisive disadvantage for your character." However, I see no reason that an extra-harsh concession (like death) should be able to bypass the group approval requirement.
The section on the Laws of Magic discusses them in terms of choice:
Whenever you choose to break one of the Laws of Magic, you’re crossing a very real line. [YS232]
Once a character has chosen to cross the line and break a Law of Magic, that decision is a part of him however you look at it. [YS233]
But then the section on the First Law says,
This is one of the easiest laws to break by accident [....] Accidental deaths can happen, and in those cases killing with magic still counts as killing when it comes to the Lawbreaker stunt. [YS235]
This seems to be an invitation to the GM to orchestrate accidents, but it's not: it's a statement of in-world assumptions, not the game's philosophy. I can say this with certainty because the very same section immediately says,
Your group should discuss how important they want the First Law to be in play. [YS236]
Ultimately, the GM needs to be careful and conscious about putting life-and-death human adversaries in front of the players. [YS236]
And makes very clear that this isn't about creating a bunch of outlaws, but about
[...] giving the First Law a strong and palpable presence in the game. A number of players might enjoy this as well, welcoming compels directed at, say, their Wizard of the White Council aspects to remind them that the First Law is an obstacle to their actions when a life is on the line. [YS236]
So that seems pretty clear: both concessions and the breaking of laws are in the hands of the group as a whole rather than the GM exclusively, and interesting narrative is at the fore of the game philosophy. To make it absolutely beyond doubt, I'll finish with this:
Who determines that a character has crossed the line? This is something that a gaming group should decide on as a policy for their specific game. [YS234]