Under the doctrine of Supremacy Clause immunity, federal officers generally cannot be prosecuted for state crimes committed while carrying out their duties. This much is well established. What has escaped the notice of the courts, however, is the nature of the immunity. Though they refer to it as “jurisdictional,” it is in fact substantive.
This is no small error. There is a difference between substantive and jurisdictional immunities, yet the current characterization of Supremacy Clause immunity glosses over it. And this distinction runs even deeper: Substantive immunities go to the merits of a case, which in turn relate to the legislature’s power to enact laws. Jurisdictional immunities, by contrast, implicate only a court’s power to rule on the merits.
The extent of this mischaracterization has been missed because it is so deeply seated. There are three contributors to this problem: the Supreme Court’s once-expansive conception of jurisdiction, the lack of a unifying theory of immunities, and the nature of Supremacy Clause immunity’s founding cases.
This mischaracterization presents fundamental semantic difficulties, as well as four practical risks of harm to the parties. First, a court may incorrectly raise the immunity sua sponte. Second, a court may improperly refuse to consider matters of equity or fairness in determining whether the immunity applies. Third, a court may unduly revisit a state judgment on the immunity’s applicability. Finally, double jeopardy would not protect the officer should a court dismiss the prosecution based on Supremacy Clause immunity.