Most students of U.S. national security law are familiar with the Posse Comitatus Act (PCA) — an 1878 statute that subjects to criminal punishment anyone who, “except in cases and under circumstances expressly authorized by the Constitution or Act of Congress, willfully uses any part of the Army or the Air Force as a posse comitatus or otherwise to execute the laws.” But what happens when a government officer violates the PCA–or the Department of Defense (DoD) regulations implementing the statute–in obtaining evidence that’s subsequently used against a criminal defendant at trial? Enter the fascinating Ninth Circuit decision handed down on Friday in United States v. Dreyer, in which a divided panel of the Court of Appeals–apparently the first federal court ever to so hold–concluded that suppression of evidence introduced at a subsequent criminal trial was an appropriate remedy when that evidence was obtained in violation of the PCA, and suppression was necessary “to deter future violations.”

At issue in Dreyer are the actions of a civilian agent of the Naval Criminal Investigative Service (NCIS), who, without any specific military trigger or target, began an investigation into online criminal activity by anyone in the state of Washington. (Although the PCA’s plain terms apply only to the Army and Air Force, Department of Defense regulations have long provided that the PCA “is applicable to the Department of the Navy and the Marine Corps as a matter of DoD policy.” And although the government argued in Dreyer that civilian agents of the NCIS aren’t covered by those regulations, the Court of Appeals unanimously disagreed.) The NCIS agent found evidence that Dreyer, a civilian, had violated federal child pornography laws, and turned it over to civilian law enforcement officials–who then used that evidence to help secure a conviction, which Dreyer appealed.

Although the three-judge panel was unanimous that the NCIS agent’s conduct did violate the relevant DoD regulations, they divided 2-1 as to whether suppression was appropriate. Writing for herself and Judge Kleinfeld, Judge Berzon (for whom I clerked in 2004-05) held that the evidence obtained by the NCIS agent must be suppressed. As Judge Berzon explained, a number of circuit courts (including the Ninth Circuit) had already held that, although suppression is not generally an appropriate remedy for evidence obtained in violation of the PCA and its implementing regulations, suppression would be appropriate in cases in which it was necessary “to deter future violations,” and not just to punish an isolated instance of unlawful conduct. (And at least two state courts had actually required suppression for PCA violations in such cases.) Here, as Judge Berzon wrote,

The extraordinary nature of the surveillance here demonstrates a need to deter future violations. So far as we can tell from the record, it has become a routine practice for the Navy to conduct surveillance of all the civilian computers in an entire state to see whether any child pornography can be found on them, and then to turn over the information to civilian law enforcement when no military connection exists. . . .

Agent Logan carried out these searches repeatedly. He was monitoring another computer at the same time that he found Dreyer’s IP address. And he was involved with at least twenty other child pornography investigations. Further, Agent Logan was not the only NCIS agent who engaged in such searches. He began carrying out these searches with two other agents at least several months before he found Dreyer’s IP address.

That a need to deter future violations exists is further supported by the government’s litigation positions. The government is arguing vehemently that the military may monitor for criminal activity all the computers anywhere in any state with a military base or installation, regardless of how likely or unlikely the computers are to be associated with a member of the military. Such an expansive reading of the military’s role in the enforcement of the civilian laws demonstrates a profound lack of regard for the important limitations on the role of the military in our civilian society.

Concurring in part and dissenting in part, Judge O’Scannlain disagreed, emphasizing “the significant costs of exclusion in PCA cases, as well as the meager evidence of PCA violations contained in the record.” Thus, he explained, this was not an appropriate case for suppression. But perhaps most interestingly, Judge O’Scannlain suggested in a footnote that suppression might never be an appropriate remedy for PCA violations, given “(1) the fact that Congress could have provided for exclusion had it thought such a remedy was appropriate; (2) the PCA provides for its own enforcement through criminal sanctions; and (3) ‘the [PCA] express[] a policy that is for the benefit of the people as a whole, but not one that may fairly be characterized as expressly designed to protect the personal rights of defendants.’”

If the application of the exclusionary rule to a PCA violation turns on the pervasiveness of the violation (and its potential impact on future cases), there will inevitably be disagreement even among the most reasonable jurists as to whether a specific case states a sufficiently pervasive violation. On this point, I have to say that I’m far more sympathetic to Judges Berzon and Kleinfeld here. As Judge Kleinfeld wrote in his separate concurrence, “We have not found another case in this circuit or our sister circuits applying the exclusionary rule to Posse Comitatus violations, but neither have we found another case in which the violations were so massive.” If the exclusionary rule should ever apply to PCA violations (and this seems to be the nub of the matter), Dreyer seems about as strong a case for applying it as the federal courts have ever seen, given the un-targeted, open-ended surveillance the NCIS agents were conducting of all computer users in particular geographic areas.

Instead, I think the real question is the one Judge O’Scannlain raised in footnote 3 of his dissent–whether suppression should ever be available for PCA violations, especially given the Supreme Court’s ever-growing hostility to the exclusionary rule in general. Thus, it will be interesting to see if the government seeks rehearing en banc in the Ninth Circuit–or, failing that, certiorari from the Supreme Court. If the argument is that this wasn’t an appropriate case for suppression, I doubt it will go anywhere. If, instead, the argument is that suppression is never an appropriate remedy for a violation of the PCA, that could be a different matter altogether…

[H/T: Eric Messinger, our assistant managing editor, for flagging this decision.]