Professor Michael Mannheimer (Northern Kentucky University) is the author of an important new article on "Unpacking Supremacy Clause Immunity." The issue of federal officer immunity from state prosecution is of obvious importance, given recent events. Thus, I am pleased to present this guest post by Prof. Mannheimer. What follows is written by him, not me (Ilya Somin):

The recent killing of Minneapolis resident Renee Good by an agent of federal Immigration and Customs Enforcement (ICE) has raised some questions, and some massive confusion, about the extent of immunity from state-law prosecution for federal agents. At one extreme, Vice President J.D. Vance, a Yale Law School graduate, proclaimed that federal agents enjoy "absolute immunity" from such a prosecution, a notion I described to a CNN reporter as "absolutely ridiculous" (yes, it is that kind of clever wordplay on my part that keeps CNN coming back for more). Even standing on its own, without guidance from the federal courts, such a claim makes no sense. First, the U.S. Supreme Court just decided recently that the President himself enjoys absolute immunity but only when exercising his "core constitutional powers," leaving for another day whether the same is true for the President's other official actions, And that was a close question, generating much disagreement over the Court's decision. It is preposterous to suggest that the President's mere underlings enjoy absolute immunity where that might not even be true of the President himself. True, the Court held that the President was immune from all prosecution for some types of official acts, while the question here is whether an ICE agent is immune only from state prosecution. But that brings me to my second point: for all intents and purposes, absolute immunity from state prosecution would ordinarily be the same as absolute immunity, full stop. Federal law does not cover most crimes potentially committed by federal agents. For example, I am unaware of any federal crime an ICE agent commits "merely" by murdering someone. A prosecution could be brought for a violation of civil rights under 18 U.S.C. § 242, but such a prosecution requires a showing beyond a reasonable doubt that the agent violated Good's rights willfully, meaning that he killed her with the specific purpose of violating her civil rights. That's a tall order. And, more to the point, a law criminalizing a deprivation of civil rights simply does not protect the same interest as a law criminalizing murder. Finally, in a regime of absolute immunity, the Federal Officer Removal Statute makes no sense either. What would be the point of Congress authorizing removal to federal court of state prosecutions of federal officers if the invariable result would be dismissal on the ground of absolute immunity? Why not just grant absolute immunity directly?

Fortunately, we do have at least some guidance from the federal courts, going back 120 years in fact. In United States ex. rel. Drury v. Lewis, two U.S. soldiers were prosecuted by Pennsylvania for murder after shooting a man suspected of stealing copper from their Army base. They sought federal habeas corpus relief, claiming immunity from state prosecution. The Supreme Court unanimously held that denial of relief was proper because of a factual dispute over whether the soldiers had shot the victim as he was fleeing, which would make the shooting justified under state law, or, instead, had shot him after he gave himself up, which would obviously be murder. Such factual disputes, the Court said, are for state court juries, not federal court judges.

Whence Vance's claims of immunity, then? For that, we have to go back even further, to 1890 and the Court's pathmarking case of Cunningham v. Neagle. There, the Court upheld the grant of habeas relief to Deputy U.S. Marshall David Neagle who was charged with murder in California state court. Neagle had killed someone who was in the process of attacking Supreme Court Justice Stephen Field. The Court held that if Neagle's conduct "was authorized . . . by the law of the United States . . . and if, in doing that act, he did no more than what was necessary and proper for him to do, he cannot be guilty of a crime under the law of the state of California." There have been only a few dozen lower federal court cases applying the doctrine of what has become known as "Supremacy Clause immunity." Courts typically view the doctrine as authorizing a federal judge to decide for themselves whether the federal agent's conduct was "necessary and proper": that is, whether the agent actually and reasonably believed that their conduct was necessary and appropriate in the exercise of their federal duties. But where there is a factual dispute, as in Drury, federal relief is barred and the case must go to a jury. That is a far cry from Vance's farcical notion of "absolute immunity." His claim that he had "never seen anything like" a state prosecution of a federal agent speaks more to his own lack of preparation before coming to the podium than to the state of the law. The cases are few and far between but they are easy to locate. Indeed, as recently as 2008, a federal district court in Minnesota itself denied immunity to a federal Border Patrol agent – held, in fact, that the claim of immunity was not even "colorable."

As I argue here, even the more limited immunity many courts have recognized is too broad, based on my close reading of the record, briefs, and decision in Neagle. For, in that case, California never disputed that Neagle's act was justified under state law. Instead, it relied solely on the contention that the federal court lacked jurisdiction on the ground that Neagle's conduct was not, as the habeas statute put it, "in pursuance of a law of the United States." Indeed, in the lower court, California's attorneys, having deemed the facts of the case irrelevant, boycotted the evidentiary hearing! Once the Court decided that Neagle's conduct was indeed authorized by federal law, even though not by a specific statute, the case was over. Thus, Neagle and Drury together stand for the modest proposition that it is for a federal court to make an initial determination whether the federal agent's conduct was indisputably lawful; if so, they cannot be charged with a state-law crime.

Neagle's protections, while very narrow, are not insubstantial. First, it allows a federal agent defendant to require court review of the state's evidence against them, as well as any evidence the defendant might proffer. In a case such as Neagle, where the defendant's conduct was indisputably justified, such a review means dismissal of the charges at an early stage. Second, Neagle authorized that review to be conducted in a friendly federal forum, an innovation largely mooted by the expansion many decades later of the Federal Officer Removal Statute, which now allows removal to federal court of virtually any state prosecution against a federal agent.

Viewed properly, "Supremacy Clause immunity" is not immunity at all. And the Neagle Court never used that word to describe what it was doing. Immunity, after all, applies irrespective of the guilt or non-guilt of the defendant, as with Presidential or diplomatic immunity. Neagle used the word "immunity" exactly once, in discussing diplomatic immunity. Neagle relief, as I prefer to call it, can be granted only when there is no dispute over the defendant's non-guilt. As Neagle itself put it, in the very next sentence after the "necessary and proper" language quoted above: "When these things are shown, it is established that he is innocent of any crime against the laws of the state."

So why does everyone mistakenly refer to Neagle relief as "immunity?" The answer, I believe, is that Neagle-type cases have been conflated with a related but different line of precedent. In Ohio v. Thomas and Johnson v. Maryland, the Court held that federal defendants could not be prosecuted under state law for conduct specifically authorized by federal statute or regulation. In Thomas, it was the use of oleomargarine in a federal veterans' home without a display of a placard identifying it as such, as required by state law. In Johnson, it was operation of a U.S. mail truck by someone without a driver's license issued by the State. In the former case, Congress had specifically authorized the provision of oleomargarine in such facilities with no mention of any disclaimer. In the latter case, federal law provided for the requirements for operation of a mail truck without specifying a driver's license from the State in which it was operated. (Presumably, some driver's license was required but Justice Holmes's characteristically terse opinion does not tell us). Such cases bestowed on the federal defendant immunity properly so-called: Thomas really did display oleomargarine without the requisite disclaimer; Johnson really did drive his truck without a Maryland license. These cases are specific instances of implied conflict preemption. The fact that the defendant was a federal agent was merely happenstance: had the Congressional authorization in Thomas applied to private nursing homes or the federal regulations in Johnson applied to private couriers, the result would have been the same.

As the Thomas Court itself recognized, Neagle is a related but distinct doctrine. Same genus, different species. And the bulk of cases in this area fall under Neagle. That is true of the killing of Ms. Good. No federal regulation specifically governed the ICE agent's conduct under these circumstances. And to whatever extent ICE regulations govern use of force more generally, there is no conflict between state and federal requirements. (If there were, I would argue that that would raise Fourth Amendment issues, but I need not get into that here).

Based on the limited evidence that we have at this point, a reasonable jury could come to differing conclusions as to whether Ms. Good was killed in self-defense. In such a case, as in any other, Neagle dictates that a jury gets to make that determination.