NRA filed suit today in the long gun reporting requirement for border state FFLs. The lawsuit is filed on behalf of Arizona FFLs, in District Court in the DC circuit. My understanding is that if you are going to file suit against the federal government, you can either sue in the state, circuit and district where the plaintiff’s reside, or you can sue the federal government where it resides.
There is some precedent that would apparently seem to give a lot of leeway to demand letters. Pretty clearly the Administration wants to see how far this hobby horse can be ridden, even to the point of implementing something clearly illegal.