Yeazell, pp. 225-228: Challenging Federal Subject Matter Jurisdiction
If youíre going to challenge federal question jurisdiction, you may attack either the jurisdiction (with a Rule 12(b)(1) motion) or the claim (with a Rule 12(b)(6) motion).† But even if you donít do either of these, you havenít necessarily waived jurisdiction because the court can bring up the issue of subject matter jurisdiction on its own.† Recall that subject matter jurisdiction is the most favored defense.
Why is so different from personal jurisdiction, which is super duper easy to waive?† I think Steve suggests that personal jurisdiction deals with the power of courts over individuals, which is an issue only as big as one person and their rights, while subject matter jurisdiction deals with the limitation of the power of the federal judiciary, which is a Big Issue that affects everybody.
Can you collaterally attack subject matter jurisdiction?† Probably not.
Dismissing a case for lack of personal jurisdiction could have a much bigger effect on a plaintiffís chance of further action than dismissing for lack of subject matter jurisdiction, but the Supreme Court has said that federal courts may use their discretion in picking which basis to use for dismissal.