By Clayton Calvin |

Imagine that the federal government prohibits you from exercising a constitutional right. Your neighbor challenges the prohibition and wins; a federal court holds that the government may not enforce it.

Now imagine that you want to engage in the very same conduct as your neighbor, inside the same judicial district where the government’s prohibition was just enjoined. The government would rely on the same law and the same legal arguments to prevent you from doing so.

You might reasonably think the government has already had its chance in court and lost — and that the matter has therefore been resolved in your favor.

Under current Supreme Court precedent, however, the federal government gets another chance. In fact, it gets a new chance each and every time someone wants to vindicate the same right under the same unconstitutional law.

Our firm, the Texas Public Policy Foundation’s Center for the American Future, represents two Texans, David McCann and Kirk Launius, in a case challenging that extraordinary privilege.

The underlying dispute involves whether law-abiding citizens may carry otherwise lawful firearms with them when they visit a post office. Federal law and Postal Service regulations prohibit carrying firearms on postal property, including by people lawfully carrying them for self-defense — a recognized constitutional right.

In 2025, several plaintiffs challenged those restrictions in the Northern District of Texas. They succeeded, and a federal judge held that the government could not enforce the restrictions upon ordinary, lawful firearm possession at post offices.

Regardless of what one thinks of the specific firearms ruling, the case exposed a broader procedural problem. Under current case law, the judgment protected only the plaintiffs who brought that particular lawsuit. So even after the Northern District of Texas held the challenged rules unconstitutional, others in the very same district still faced the same restrictions.

McCann and Launius were among those still affected. So, we filed a second lawsuit on their behalf in the same federal district. We raised a question far beyond firearms: How many times should the federal government get to litigate the same issue after it loses?

Ordinarily, our legal system has an answer. The doctrine of collateral estoppel, also called issue preclusion, prevents a party from repeatedly litigating an issue that has already been fully and fairly decided against it.

The principle is straightforward: litigation must eventually end. A losing party generally cannot keep demanding a new adjudication of the same issue in hopes that a different judge will give it a better answer.

But in 1984, the Supreme Court created a special exception to this doctrine for the federal government.

In United States v. Mendoza, the Court held that the federal government generally cannot be subjected to what lawyers, in a mouthful, call “nonmutual offensive collateral estoppel.” In other words, someone who was not a party to the first case normally cannot use the government’s previous loss to prevent it from relitigating the same issue against him or her.

The Court offered practical reasons for creating this exception for the federal government. Federal litigation occurs across the country, and important legal questions should be allowed to develop as the government defends its position in multiple courts. The government also should not feel compelled, the Court thought, to appeal every adverse district-court ruling for fear that one loss will bind it forever nationwide.

Those concerns may explain the Court’s reasoning, but they come at a real cost: they allow the federal government to keep relitigating issues it has already lost, forcing Americans into the uphill battle of perennially fighting for the same recognized rights. In this way, the federal government effectively holds a Sword of Damocles over the nation even after judges rule against it.

That problem has become more serious after the Supreme Court’s recent decision in Trump v. CASA. Whereas Mendoza limits a plaintiff’s ability to avoid redundant litigation, CASA limits the relief a plaintiff can obtain after winning it. In CASA, the Court held that, in general, one judge may not simply block a federal policy throughout the whole country, because relief usually extends only to the parties who actually brought the case. The result is that one person can defeat an unlawful government action, and yet everyone else remains subject to its force — and under Mendoza, if prosecuted, must litigate the same issue in its entirety.

Our case is about whether Mendoza should really require that result for everyone else within the same federal district.

McCann and Launius are not trying to take one district judge’s decision and impose it nationwide. They sued in the very same federal district in which the government had already litigated and lost the issue. Yet the district court concluded that Mendoza categorically foreclosed our collateral-estoppel argument.

We are appealing that ruling to the U.S. Court of Appeals for the Fifth Circuit.

And events since these cases were filed have made the problem even clearer.

The government has since dropped its appeal of the original post office ruling, leaving that decision in place. And the Trump administration’s own Office of Legal Counsel has concluded that the challenged restrictions are indeed unlawful as applied.

So the government lost the underlying issue in court, abandoned its appeal, and has now itself concluded that the challenged regulatory prohibition violates the law. Yet under the district court’s reading of Mendoza, another citizen in the same district still cannot invoke that earlier judgment to protect himself from litigating the issue all over again.

That result is not necessary to preserve healthy disagreement among courts. It is disorder within the same court system.

And after CASA, the problem extends far beyond this case. If judicial relief ordinarily protects only the parties who sue, while Mendoza permits the federal government to relitigate the same issue against every new plaintiff, then constitutional rights are effectively dispensed by the government at sufferance — even within the same federal district.

The alternative does not have to mean that one district judge dictates federal law to the entire country. Different courts may remain free to disagree, legal questions may develop through the judicial system, and appellate courts may establish binding precedent for broader jurisdictions, as CASA contemplated.

But there is a vast difference between allowing different courts to disagree and requiring the same court system to reconsider the same issue every time a new citizen walks through the courthouse door.

Mendoza described itself as protecting the legitimate development of federal law. In the post-CASA world, it should not become a rule of perpetual relitigation.

When the government loses, it should have the same basic choices other litigants have: accept the result or appeal it.

It should not have an endless supply of second chances.

Originally published by the Daily Caller News Foundation.

Clayton Calvin is a contributor to the Daily Caller News Foundation and an attorney for the Texas Public Policy Foundation’s Center for the American Future.