In the USA there's the USA branch, overseeing JW activity in the USA, and there's the world HQ that oversees the world wide activity of JW.
USA elders would normally contact the USA branch, not HQ. Just as German elders would contact German branch, not HQ.
I guess HQ legal dept. is contacted by the legal dept. of the difference branches, and/or (if needed) by international organizations like the UN, OSCE, EU courts, etc.