The Justice Department rules that soldiers may chase and arrest civilians who trespass through a border defense area and then leave it

What happened

On August 14, 2026, the Justice Department’s Office of Legal Counsel concluded that the Posse Comitatus Act does not bar military personnel from pursuing and arresting civilians who trespass through a national defense area along the southern border and leave it before they can be detained. The arrest must be in the immediate vicinity.

Since April 2025 the Pentagon has designated six national defense areas along the border, strips of federal land attached to military bases, so that soldiers can arrest migrants crossing them for trespass. The Department of War’s general counsel asked whether troops could also arrest people who got out before being caught.

The opinion relies on 10 U.S.C. 2672 and the military-purpose exception, rejects the argument that mostly empty national defense areas lack a military nexus, and expresses no view on arrests far from the trespass. Lawfare’s Chris Mirasola wrote that the statute’s off-base authority covers only civilian personnel and that the logic admits no limit.

Who benefited

The Department of War and Northern Command gained legal cover to use soldiers as arresting officers beyond the lines they drew themselves. The White House, whose April 2025 directive made the military the lead actor at the border, also benefited.

Who wanted something

Department of War General Counsel Earl Matthews requested the opinion in April 2026. The administration’s border and homeland-security leadership has sought steadily broader military roles. OLC under Assistant Attorney General T. Elliot Gaiser supplied the authorization.

Who lost out

Migrants and anyone else near the border can now be chased down and arrested by soldiers rather than civilian agents. The Posse Comitatus Act, whose purpose since 1878 has been to keep the army out of civilian policing, loses force. Border communities lose the line between military and police.

Why it matters

Soldiers may now arrest civilians off base for a trespass, and the opinion sets no limit on how far off base. Critics said its reasoning is unmoored from case law and has no limiting principle. Whether an installation is large enough to count as a military one is decided by the department that polices it.

Sources U.S. Department of Justice, Office of Legal Counsel (primary)Lawfare