[Editors’ note: This essay is one in a series—the Good Governance Papers—organized by Just Security. In these essays, leading experts explore actionable legislative and administrative proposals to promote non-partisan principles of good government, public integrity, and the rule of law. For more information, you can read the Introduction by the series’ editors.]

In Good Governance Paper No. 6 (Part 1), I argued that we should reform the Insurrection Act, a critical law that provides broad authority to the president to deploy federal military forces on American soil. Specifically, we should reinvigorate Congress’ role in domestic military operations by placing new reporting and consultation requirements whenever the Insurrection Act is invoked. Beyond the Insurrection Act, several additional laws govern use of the military in the U.S. They include the Posse Comitatus Act, Section 502(f) of Title 32 of the U.S. Code, and laws governing military operations in the nation’s capital. All three are ripe for reexamination and are discussed in detail below.

1. Clarify the Posse Comitatus Act’s Scope & Applicability

The Insurrection Act is the most important statutory exception to the Posse Comitatus Act (PCA), the default statutory rule that the federal military does not generally engage in domestic law enforcement matters. As a textual matter, the PCA prevents federal (“title 10”) Army and Air Force personnel from serving in an active law enforcement capacity. As a regulatory matter, the Department of Defense (DoD) applies these PCA restrictions to the Navy and Marine Corps. Courts have interpreted the PCA to bind National Guard troops when on federal duty. The U.S. Coast Guard—which is organizationally part of the Department of Homeland Security for most operations—serves as the U.S.’s maritime law enforcer and remains free from the PCA’s restrictions. Also exempted from the PCA’s reach are the often–militarized civilian federal troops of the Departments of Justice and Homeland Security that appeared in combat gear on the streets of Portland and other cities this summer.

As I have argued elsewhere, the PCA (just 51 words) has taken on a certain talismanic status within the national security community and is in need of modernization and clarification. This is somewhat remarkable and unintended, particularly in light of the PCA’s ignoble origins. Passed in 1878, the PCA and the removal of federal military forces from the Post-Civil War South—troops that were in place to protect the rights and liberties of recently freed slaves—marked the end of Reconstruction and a new era of oppression and violence targeting African Americans.

Today, the military’s precise role in domestic military operations is governed by an increasingly convoluted array of exceptions, judicial holdings, and Department of Defense guidance on what constitutes a PCA violation. Last revised in 1947 in conjunction with the National Security Act that created the Air Force and our modern national security bureaucracy, the PCA’s day-to-day application is more heavily governed by regulations and court opinions than by the statute itself. Department of Defense regulations, for example, cite 14 specific statutes that authorize the armed forces to participate directly in law enforcement matters. And even where it does squarely apply, the PCA only prevents federal military forces from exercising a direct role in law enforcement, such as making arrests and searching or seizing people or property. The PCA does not restrict federal military forces from providing indirect assistance, such as providing logistical support to local law enforcement entities. Further, federal military forces may directly participate in law enforcement matters when performed primarily for a “military purpose.” Unfortunately, the PCA itself does not provide a bright line between direct and indirect assistance, much less define “military purpose” or say anything about militarized federal civilian troops.

Creation of a new branch of the armed forces (the Space Force), the continual militarization of federal civilian personnel, and persistent uncertainty about how PCA works makes this the right moment for Congress to modernize the statute. I recommend that the PCA be updated to expressly include all branches of the armed forces—the Army, Air Force, Marine Corps, Navy, and Space Force. The Coast Guard and state National Guard forces reporting to their respective governors should remain exempt as a statutory matter. Employment of the District of Columbia National Guard is truly unique and is discussed below. Similar to my Insurrection Act proposals, we should also require notification whenever a PCA exception is used.

The Posse Comitatus Act should be amended at 18 U.S.C. § 1385 (a)-(c) to read as follows (new language in italics):

(a) Whoever, except in cases and under circumstances authorized by the Constitution or Act of Congress, willfully uses any part of the Army, Navy (to include Marine Corps), Air Force, or Space Force as a posse comitatus or otherwise to execute the laws shall be fined under this title or imprisoned not more than two years, or both. Any member of the Army, Navy, Air Force, Marine Corps, or Space Force is prohibited from directly participating in a search, seizure, arrest, detention, or similar activity unless participation in such activity is otherwise authorized by Congress.

(b) Within 48 hours, anyone that invokes an exception to the Posse Comitatus Act must notify the Secretary of Defense (or designee) and the Senate and House Armed Services Committee, addressing the legal basis for the use of military forces.

(c) This section does not apply to the Coast Guard, state National Guard forces operating under the control of their respective state Governors, or military law enforcement forces on federal military installations.

In addition, the PCA should clarify what is meant, exactly, by both “executing the laws” and “military purpose.” For non-military federal law enforcement, Congress should mandate consistent uniform regulations for each federal law enforcement agency and require formal notification procedures to the state and local authorities prior to deploying. This is analogous to the amendment to the Insurrection Act proposed in Good Governance Paper No. 6 (Part 1) and is consistent with Defense Department uniform regulations.

2. Clarify What is Meant by “Other Duty” in Section 502 (f)

Congress should clarify 32 U.S.C. § 502(f), a statute titled “required drills and field exercises.” This provision was last revised in the aftermath of 9/11 to facilitate the National Guard responding to ongoing terrorist threats and future attacks. As my colleague (and former Army JAG) Professor John Dehn stated, “Nobody writing this new provision likely viewed it as ever becoming some kind of workaround for the Insurrection Act.” But that was exactly what occurred this summer when this fairly obscure provision was repurposed by the U.S. Department of Justice as an Insurrection Act loophole by Attorney General Barr.

Specifically, the statute states that a member of the National Guard may “be ordered to perform training or other dutyunder Secretary of the Army regulations. This may include “support of operations undertaken by the member’s unit at the request of the President or Secretary of Defense.” What does “other duty” mean? The statute does not define it, but we do know that the Justice Department construed it as a back-door mechanism to deploy the National Guard under the direction of the President. This occurred without the formal federalization of the Guard that the Constitution envisions and without invoking the Insurrection Act. This loophole should be closed. Congress should clarify when, precisely, this authority can be invoked and what is expressly meant by “other duty.”

A new 32 U.S.C. 502 (f)(1)(B) should read:

“other duty” is defined as support to federal defense support to civil authorities. It does not include use of force, nor direct support to or participation in law enforcement. Any military use of force or direct support to law enforcement must comply with the Insurrection Act at 10 U.S.C. §§ 251-255, Posse Comitatus Act, 18 U.S.C. § 1385, and applicable Department of Defense regulations and instructions.

 3. Clarify Authority for Military Operations in the Nation’s Capital

 On June 1 in Lafayette Square, the world watched in horror as federal Park Police and National Guard troops forcibly cleared out protestors, and military helicopters engaged in aggressive maneuvers to intimidate peaceful protestors elsewhere in the capital of the United States of America. Events in the nation’s capital exposed surprisingly murky legal authorities governing military operations in the District of Columbia. Several problems stand out.

First, unlike state governors, the elected chief executive of the District of Columbia, the Mayor of the District of Columbia, has no direct command authority over the D.C. National Guard (DCNG). The DCNG is a true military anomaly: it resides in a federal district governed by a mayor and city council, but under the D.C. Code the President of the United States is “Commander-in-Chief of the militia of the District of Columbia,” whether or not it has been federalized. Under a 1969 Executive Order and longstanding memorandum, the Secretary of the Army and Commanding General of the DCNG exercise operational control over its Army and Air Force elements.

Second, it remains unclear who has the authority to bring outside state National Guards into the District of Columbia or to any state. This uncertainty was recently made clear by the D.C. attorney general when over 3,800 military troops from 11 states arrived in the District following the death of George Floyd. Nearly all of these troops hailed from states with Republican governors. And they entered the District without the Mayor’s permission. The U.S. Attorney General, William Barr, justified this based upon a relatively obscure provision of the U.S. Code, discussed above.

As the senior elected government official in the nation’s capital (with a population of over 700,000 people – more than two states), the Mayor should have a more substantive legal role in both DCNG operations and determining when state National Guards from outside the area are welcome. Military operations in D.C. were the recent subject of congressional hearings and a D.C. Guard Army Major whistleblower complaint. Congress should follow up on these hearings to provide more explicit guidance on the legality and chain of command of military operations in D.C.

Under D.C. Code § 49-409 as passed by Congress, the President of the United States is at all times the Commander-in-Chief of “the militia of the District of Columbia.” This law should be modified as follows:

The Mayor of the District of Columbia is at all times the Commander in Chief of the District of Columbia National Guard (DCNG) when on non-federal duty. In that capacity, she acts with commensurate authorities of a state Governor under Title 32, U.S. Code.

In addition, Congress should more generally clarify the role of state Governors (or Mayor in the case of DC) prior to any outside National Guard performing duty in her jurisdiction. Again, the law is unclear on the authority for outside military units to operate in any state, territory, or the District of Columbia. This is similar to a provision proposed by Del. Eleanor Holmes Norton (D-DC). I propose a new 32 U.S.C. § 502 (g):

Members of state National Guards may perform official functions—either in a law enforcement or support to civil authorities capacity—on non-federal duty within other states, territories or the District of Columbia at the request and invitation of the chief executive of that jurisdiction.


The United States has had strong traditions of civilian control of the military and exclusion of the military from engaging in law enforcement since the nation’s founding. The Trump Administration’s threatened and actual use of the military showcase the need to rely less on historical norms and more on legal authority. As my colleague Eugene Fidell has just noted for Just Security, the current Administration has ruptured longstanding civil-military norms, and military personnel may be drawn into situations for which there is simply no precedent. The four legal clarifications about domestic use of the military I have discussed in this essay and my prior essay are a good place for Congress to start.