If the Austin Shooter Had Survived, Could We Denaturalize Him?

Denaturalization is not punishment, but an ‘undoing of that which should not have been done in the first place’

By George Fishman on March 3, 2026
Iran flag

As we all know, on Sunday, naturalized citizen Ndiaga Diagne murdered three people and injured more than a dozen more in a mass shooting in Austin, Texas. Tony Plohetski, Austin Sanders, and Alexis Simmerman have reported in the Austin-American Statesman that Diagne “was wearing clothing at the time of the shooting that bore the words ‘Property of Allah’ and an image of the Iranian flag, raising questions about whether Diagne may have been motivated by the joint U.S.-Israeli strikes on Iran”.

According to the Department of Homeland Security, Senegalese immigrant Diagne became a naturalized citizen in 2013. Does anyone really think that when naturalized, he actually met the statutory requirement of being “a person of good moral character, attached to the principles of the Constitution of the United States, and well disposed to the good order and happiness of the United States”? While Diagne was killed by police during his murder spree, this raises the question of whether he could have been denaturalized had he survived. The short answer is “maybe”.

The U.S. Constitution grants Congress alone the authority to prescribe rules for naturalization. In addition to requirements like the one mentioned above, federal law has long required the final step toward naturalization to be taking an oath to support and defend the Constitution and renounce all allegiance and fidelity to an immigrant’s prior country of citizenship.

It is a Trump administration civil law enforcement priority to “prioritize and maximally pursue denaturalization proceedings in all cases permitted by law and supported by the evidence”. What do federal law and the Constitution permit?

The Supreme Court explained in its 1946 decision in Knauer v. United States that “[c]itizenship obtained through naturalization is not a second-class citizenship” but “carries with it the privilege of full participation in the affairs of our society”. The Court concluded in its 1981 decision in Fedorenko v. United States that “once citizenship has been acquired, its loss can have severe and unsettling consequences” and the government “carries a heavy burden of proof” in a denaturalization proceeding. However, at the same time the Court made clear that “there must be strict compliance with all the congressionally imposed prerequisites to the acquisition of citizenship” and that “Failure to comply with any of these … renders … citizenship ‘illegally procured,’ and naturalization that is unlawfully procured can be set aside.” Denaturalization does not constitute punishment. It is, rather, as the U.S. District Court for the District of Maine concluded in its 1985 decision in United States v. Klimavicius, an “undoing of that which should not have been done in the first place”.

The Immigration and Nationality Act provides that the federal government can seek to denaturalize, or revoke the citizenship, of those who illegally procured naturalization or procured it by concealment of a material fact or by willful misrepresentation.

The Supreme Court ruled in its 1943 decision in Schneiderman v. United States that in a denaturalization proceeding, in order to prove that a citizen lacked attachment to the Constitution at the time of naturalization the government must provide “‘clear, unequivocal, and convincing’ evidence which does not leave the issue in doubt”. However, in 1980, the Court in Vance v. Terrazas seemingly indicated that Congress would have the power to substitute a lower standard of proof.

It is fair to conclude that, under the Constitution, naturalization may only be revoked where it was illegally procured in the first place. So to what extent, if any, may the government revoke naturalization based on behavior engaged in or beliefs expressed post-naturalization?

As the Fourth Circuit concluded in its 1944 decision in Orth v. United States, post-naturalization behavior and beliefs “can at best rise only to the level of evidential facts” as to a citizen’s behavior and beliefs at the time of naturalization. While the Supreme Court in its 1944 decision in Baumgartner v. United States expressed dubiousness as to the “logical validity” of the “presumption that disqualifying views expressed after naturalization [are] accurate representations of [a citizen’s] views when he took the oath”, the Second Circuit concluded in its 1950 decision in United States v. Eichenlaub that the Supreme Court had “not h[e]ld that evidence of subsequent acts would as a matter of law be insufficient proof of an earlier fraudulent intent”.

The Seventh Circuit explained in its 1943 decision in United States ex rel. Harrington v. Schlotfeldt that “Certainly allegiance to our Government and the principles of its Constitution cannot have been very deep or sincere if it could so easily be supplanted within a few years by an ideology [Nazism] which is the complete antithesis of everything for which our Constitution stands.”

And as the Senate Judiciary Committee explained in 1950, federal courts had been of the opinion that “if loyalty was unable to stand the test of an armed conflict against the naturalized person’s country of origin, it was absent from the beginning”. The committee concluded, however, that during World War II the Supreme Court had begun to hold the government “to such a strict standard of proof that it became very difficult to” denaturalize citizens with Nazi sympathies. The committee thus recommended enactment of a new federal law providing that “joining a [subversive] organization within 5 years after naturalization shall be presumptive evidence that naturalization was obtained by a willful misrepresentation or by concealment of a material fact”. But the committee “emphasize[d] that this … is not intended to place a condition subsequent upon naturalization”, but rather simply to “create a rule of evidence” as to whether naturalization was obtained unlawfully.

The committee’s recommendation was enacted into law in the “Internal Security Act of 1950” and (in modified form) remains good law today: Joining a subversive organization within five years of naturalization “shall be considered prima facie evidence that [a citizen] was not attached to the principles of the Constitution … and was not well disposed to the good order and happiness of the United States at the time of naturalization, and, in the absence of countervailing evidence, it shall be sufficient … to authorize” denaturalization.

One difficulty in assessing this presumption’s constitutionality is that it has rarely been invoked and as far as I can tell has not been the subject of a federal court decision. But we can look for guidance to federal court decisions regarding other statutory denaturalization presumptions taking the same “prima facie evidence/countervailing evidence” form.

In its 1913 decision in Luria v. United States, the Supreme Court utilized a test the Court had laid out in 1910 in Mobile, Jackson & Kansas City R. Co. v. Turnipseed: that in order for “a legislative presumption of one fact from evidence of another … not [to] constitute a denial of due process of law, or a denial of the equal protection of the law, it is only essential that there shall be some rational connection between the fact proved and the ultimate fact presumed, and that the inference of one fact from proof of another shall not be so unreasonable as to be a purely arbitrary mandate”. The Court concluded that the denaturalization presumption it was reviewing met this test. However, the Court noted that “Congress has indicated its opinion that the intervening period may be as much as five years without rendering the presumption baseless. That period seems long.” The Court stated that “yet we are not prepared to pronounce it certainly excessive or unreasonable”, but cautioned “we are of opinion that, as the intervening time approaches five years, the presumption necessarily must weaken to such a degree as to require but slight countervailing evidence to overcome it”. However, “On the other hand, when the intervening time is so short as it is shown to have been in the present case, the presumption cannot be regarded as yielding to anything short of a substantial and convincing explanation.”

In 1980, the Ninth Circuit considered essentially the same statutory provision and concluded in United States v. Banafshe that “[it] is a valid exercise of Congress’ authority to enact rules of evidence and procedure”, noting that the Supreme Court in Luria “had upheld the constitutionality of a predecessor statute”. The court concluded that “Any danger that the presumption is too broad is eliminated by [the] requirement that the strength of the presumption vary with length of time elapsed between naturalization and the [post-naturalization act]. We conclude that [the statute] is a rational exercise of Congressional judgment.”

To sum up, the government can constitutionally utilize evidence of post-naturalization behavior/beliefs in order to demonstrate that a citizen had unlawfully procured naturalization, and thus in order to revoke their citizenship. It is also constitutional to rely on prima facie evidence/countervailing evidence presumptions — as long as there is a rational connection between the proscribed post-naturalization act and the citizen’s state of mind at the time of naturalization. However, the longer the time between naturalization and the commission of the proscribed act, the less convincing the evidence the citizen has to provide to defeat the presumption.

Ndiaga Diagne was naturalized 13 years ago. At this juncture, it does not seem that he was “a member of or affiliated with any [subversive] organization, membership in or affiliation with which at the time of naturalization would have precluded such person from naturalization”, as such organizations are defined in federal law. The vile crimes that Diagne has just committed do not necessarily mean that at the time of his naturalization he was not “a person of good moral character, attached to the principles of the Constitution of the United States, and well disposed to the good order and happiness of the United States”, for it is at least possible that he could have been “radicalized” after becoming a citizen. But, had Diagne survived, more evidence of his behavior and beliefs — either before or after naturalization — could have come to light that would have allowed the government to revoke his citizenship.