The Question of “Regular Forces” and the National Guard

Jun 2

By: Taariq Ahmed
Edited by: Alexa Tan and Annie Jiang

The Trump administration’s deployments, and threats to deploy, the National Guard to several blue cities during the first year of his second term, citing allegations that immigration enforcement agents were underprotected and that crime was rising, have triggered legal battles on when it is appropriate to use troops domestically. [1] [2]

The National Guard, a branch of the military composed of civilian soldiers, is one of the few military forces that can operate within the United States and typically responds to natural disasters and civil unrest. [3] However, these recent deployments were framed as necessary backup for local authorities. For example, the Trump administration sought to deploy the National Guard to the Chicago area, but the Supreme Court ruled against it on December 23, 2025. [4] Although the decision was only preliminary, the administration has since quietly scaled back its efforts to send troops to cities like Chicago. Given that these legal challenges have raised questions about the future of such domestic deployments, what are the limits of presidential authority to deploy troops domestically, and are courts willing to constrain the executive branch when it invokes emergency powers? [4]

The dispute over “regular forces” illustrates how technical statutory language can emerge as a key point in defining the limits of presidential emergency powers. At the heart of the Court’s decision to block the Guard’s deployment to Chicago were two words: “regular forces.” To justify federalizing the Guard, the Trump administration invoked its authority to respond to “rebellion or danger of a rebellion,” arguing that immigration-related protests in the area required additional support for federal agents under strain. [5] The legal dispute centered on whether the administration was truly “unable with the regular forces” to execute the law and what qualifies as “regular forces.” The administration contended that the term referred to civilian law enforcement personnel, like federal immigration agents, meaning the Guard could be used if those agents required backup. Illinois officials, however, argued that “regular forces” referred to the U.S. military itself. Thus, they made the case that not only had the administration failed to prove that it was “unable” to enforce the law with the military, but that it could not even legally call on the military as domestic police in the first place. The Court agreed that under the 1878 Posse Comitatus, which generally prohibits the use of federal military forces in civilian law enforcement without specific statutory or constitutional authorization, that the administration had not proved why the military should be deployed in the first place. [5] [6]

A majority of the Court sided with Illinois, concluding that the administration had not met its burden of proving either that existing “regular forces”—which the Court agreed was the U.S. military—were inadequate or that the circumstances justified invoking emergency authority in the first place. [5] The Court further held that the administration had failed to demonstrate why additional force was necessary to protect federal agents and property, as it had claimed. This shows how the threshold for deploying troops domestically often hinges on how the president interprets terms like “regular forces” or “rebellion.” Courts, in turn, tend to treat those definitions carefully, recognizing that seemingly technical language can shape how, and whether the National Guard is used for civil law enforcement within the U.S. [5]

The Chicago ruling was not a one-off. Courts across several cities increasingly found the Trump administration’s attempts to employ the National Guard for domestic law enforcement unlawful. In Chicago, the Court deemed that the bar was too high for the government to deploy the military itself—let alone the National Guard. This decision was an example of the Court deciding that the conditions did not warrant use of the Guard. This happened elsewhere, too. In September, a federal judge ordered the end of the Trump administration’s deployment in Los Angeles, California, on the grounds that it violated the Posse Comitatus Act. [6] By December, the same judge decided the administration must end the National Guard deployment in the state. [7] In Portland, Oregon, a judge issued a decision in November that prominently barred deployment of National Guard troops, shooting down arguments similar to the Chicago case from the government that protests had amounted to “rebellion.” [8] The judge also found the deployment broke the Constitution’s 10th Amendment, which defers powers to states that are not explicitly delegated to the federal government. [8] By the end of 2025, Trump announced he would be removing troops from each of the three cities. [9] The withdrawals suggested that the court rulings had begun to hamper the administration’s strategy of using the National Guard as backup for federal law enforcement. The challenges demonstrated that even when presidents invoke emergency powers, the courts may demand evidence that such powers are warranted.

More broadly, the Chicago dispute exposed long-standing tensions between the executive and judicial branches over the limits of presidential emergency powers, illustrating how statutory interpretation—even of just two words—can constrain the deployment of military force within the United States. This period revealed that presidents and courts can disagree over law enforcement authority, and how longstanding laws may contain exceptions while still imposing a high threshold for invoking them.