Date Filed: December 17, 2025
Original Court: U.S. District Court for the Northern District of Texas
Case Status: Pending
Federal law and regulations prohibit carrying firearms on U.S. Post Office property, including parking lots, even when a firearm is lawfully carried for self-defense. A gun owner who drives to the post office to mail a package with a legally carried handgun in the car is technically committing a federal offense punishable by up to one year in prison.
This case is not just about the Second Amendment, however. It asks a basic question of fairness: if a court has already ruled that a law is unconstitutional, should the government be allowed to keep prosecuting and forcing new citizens to file identical lawsuits in the very same court?
In September 2025, the U.S. District Court for the Northern District of Texas held that the federal ban on carrying firearms at ordinary post offices violates the Second Amendment. The court issued an injunction preventing the federal government from enforcing the law. But because of the Supreme Court’s recent decision in Trump v. CASA, that injunction protects only the plaintiffs in that case. Even though the court found the law unconstitutional, the government may still enforce it against everyone else.
TPPF represents two law-abiding gun owners who were not parties to the earlier lawsuit. We filed suit in the same court, asking it to apply its previous ruling to protect other law-abiding citizens in the same district.
Normally, when someone loses an argument in court, they cannot simply raise the exact same argument again in a later case involving the same legal issue. This longstanding rule is called “collateral estoppel,” or “issue preclusion.” The Supreme Court’s decision in United States v. Mendoza, however, created an exception for the federal government. As a result, even after a court has ruled that a law is unconstitutional, the government can continue to prosecute under it, making the same arguments previously rejected by a court.
Courts in different parts of the country may reasonably reach different conclusions while the law develops. But we believe the federal government should not be allowed to relitigate the same unsuccessful arguments before the same court, in the same district, against one citizen and then his neighbor. This case asks whether courts should have greater authority to prevent that kind of repetitive litigation and better protect citizens whose constitutional rights have already been recognized.
Case Documents:
Plaintiffs’ Motion for Summary Judgment
Defendant’s Response in Opposition to Motion for Summary Judgment