i'm confused though. how come a defendant can challenge the original court's jurisdiction in the enforcement action through a collateral attack?
And so that means if a court decides a case, and it turns out that it was in the wrong venue the whole time, the parties can never object to the lack of jurisdiction even on appeal?
I do disagree however about some aspects because personal jurisdiction for federal courts is not limited by the constitution but by 4k. Kind of funny right? Nothing in the constitution limits the territorial power of the federal court, just statutes.
Also diversity subject matter is completely statutory as well. (Article 3 gives the courts original jurisdictional power over other issues and federal question).