This might or might not surprise you, but the BATFE essentially makes the law, interpreting 8 decades of often unclear statutory law. The latest example of this is their recent "On second thought, M885 ammo is bad"---although the statutory law sure seems to be clear to me, but I've come across lawyers on our side who think it's debatable.
Challenging them is very dangerous, they have an odd habit of using any and all means to destroy people they get upset with, even their own agents, e.g. https://en.wikipedia.org/wiki/Jay_Dobyns And most Federal courts and judges are not exactly on our side.
Back when people were wondering how we could get "the people" upset enough about the NSA et. al. to have the same effectiveness as "the NRA" (really, the nation's gun owners), I pointed out more that a few atrocities would have to be committed and publicized. That "worked" for us because the BATFE is probably the dirtiest and nastiest of the Federal law enforcement agencies.