The Caravan ‘Invasion’ and Limits on Domestic Use of the American Military
Christopher Dunn
Christopher Dunn

Christopher Dunn

For those concerned about a constitutionally unhinged presidency, Donald Trump’s decision at the end of October to deploy what has grown to be about 5,600 active military personnel to Texas and other southwest border states in response to a caravan of Central American migrants fleeing violence in their home countries was alarming. And that alarm only deepened on November 20 when the White House authorized those troops to use deadly force.

From the founding of the United States, deployment of the federal military within the country has been a source of deep concern, and a longstanding federal statute—the recently much-mentioned Posse Comitatus Act—makes it a crime for federal military personnel, except in narrow circumstances, to engage in domestic law enforcement. (Posse comitatus—literally “power of the country”—was defined at common law as all those 15 and older whom a sheriff could call for assistance in preventing civil disorder.) Nonetheless, precious little law—including no meaningful Supreme Court precedent—addresses the deployment of American troops domestically. The ongoing presence of the military in the southwest United States provides a useful opportunity to examine the little authority that exists.

In approaching this examination, it is important to recognize that domestic deployment of federal troops is permissible and appropriate in highly unusual circumstances, the Civil War being the most notable example. And to be sure, federal troops have been used domestically in several momentous situations, including the unconstitutional internment of about 120,000 adults and children of Japanese descent during World War II and the post-World War II enforcement of federal court orders to desegregate Southern schools. But what makes Trump’s deployment action so disconcerting—and thus so worthy of scrutiny—is that he ordered the deployment days before a major federal election, seemingly for political purposes. Given Trump’s often reckless use of his extraordinary presidential power, reasonable people could worry that the current military deployment might be a prelude to further use of the military for Trump’s political purposes.

Constitutional and Statutory Framework



Discussion of the limits on presidential power to deploy troops domestically starts with the Constitution. At the outset, of course, Article II, §2 provides that “the President shall be Commander in Chief of the Army and Navy of the United States,” and §3 provides broadly that “he shall take Care that the Laws be faithfully executed.” As for Congress, §8 of Article I includes the power to “provide for calling forth the Militia to execute the Laws of the Union, suppress Insurrections and repel Invasions.” Finally, the Bill of Rights contains some provisions obliquely bearing on the issue, with the Third Amendment providing that “no Soldier shall, in time of peace be quartered in any house, without the consent of the Owner, nor in time of war, but in a manner prescribed by law” and the Second Amendment providing that “a well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed.”

Congress has partially filled this sparse constitutional landscape with three pieces of legislation. First is the Insurrection Act, originally enacted in 1807 and now codified at 10 U.S.C. §§251-55, which expressly authorizes presidential law-enforcement deployment of federal troops as follows: