Posse Comitatus Explained: How It Affects Military Law

The Posse Comitatus Act plays a crucial role in upholding the U.S. tradition of separating military power from civil authority. Its effects can be felt throughout military law, domestic security policies, and the responsibilities of service members.

If you’re a service member with questions or concerns about your responsibilities or if you believe there is a conflict between your orders and the PCA, it’s time to contact Daniel Conway & Associates. 

Our legal team can guide you through the nuances of the PCA to explain any discrepancies you may be experiencing. Call Daniel Conway & Associates today to schedule a free consultation regarding any PCA concerns.  

Introduction to the Posse Comitatus Act (PCA)

The Posse Comitatus Act of 1878 (PCA) is a foundational piece of federal legislation that sharply defines the boundary between military and civilian authority in the United States. Enacted in 1878, the PCA prohibits the use of the U.S. Army and (later) the Air Force to execute domestic laws unless expressly authorized by the Constitution or Congress. 

Born out of post-Reconstruction era concerns about federal troops being used for law enforcement in Southern states, its purpose is to uphold civilian control and prevent the military from becoming a tool for domestic governance. 

Having a thorough understanding of the PCA is essential for legal professionals, policymakers, and military personnel alike. It underscores the legal boundaries of military action on American soil and shapes how service members engage with domestic operations. 

Key Provisions of the Posse Comitatus Act

The original Posse Comitatus Act states: 

“Whoever, except in cases and under circumstances expressly authorized by the Constitution or Act of Congress, willfully uses any part of the Army or the Air 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.” 

Several key elements emerge from this statute:

• Scope: Initially, the PCA applied only to the U.S. Army. It was later extended to the Air Force when the latter became a separate branch in 1947. 
• Navy and Marine Corps: While the PCA does not explicitly mention the Navy or Marine Corps, Department of Defense (DoD) policy extends the PCA’s restrictions to these branches. 
• Space Force and Coast Guard: The Space Force, as a component of the Department of the Air Force, is subject to PCA constraints. The Coast Guard, however, operates under the Department of Homeland Security during peacetime and is exempt from certain regulations when conducting law enforcement missions. 
• Enforcement: Violations are rare and typically addressed through military discipline rather than criminal prosecution. However, the penalties listed include fines and imprisonment. 

It’s crucial to note that the PCA does not prohibit all forms of military involvement in civilian matters. Instead, it restricts direct military enforcement of domestic laws. For example, the military cannot arrest citizens, conduct searches, or seize property, unless explicitly authorized by Congressional law or an amendment to the Constitution. 

Exceptions to the PCA

While the PCA establishes a general prohibition on using military personnel in law enforcement roles, Congress and the Constitution have created several exceptions. Authorized through federal statutes, these exceptions outline when and how the military can assist in domestic operations:

National Emergencies Act and Insurrection Act

The Insurrection Act of 1807 is one of the most significant exceptions to the PCA. It allows the President to deploy federal troops domestically in cases of rebellion, lawlessness, or insurrection when local authorities are unwilling or unable to maintain order. 

Notably used during the 1992 LA riots, this act overrides many PCA limitations. 

Support to Civilian Law Enforcement Agencies (SCLEA)

The military is permitted to support civilian law enforcement agencies by providing:

• Equipment and facilities
• Training
• Technical support
• Intelligence and surveillance

However, the relevant statutes do not permit the military to engage in direct law enforcement activities like arrest or search and seizure. 

Disaster Relief and Emergency Assistance

Military forces may assist during natural disasters under the Stafford Act and Department of Defense Directive 3025.18. Their role is typically limited to logistics, transport, medical aid, and infrastructure restoration, avoiding direct law enforcement activities. 

Military Police on Base

Military police and commanders retain the authority to enforce laws on military installations or in matters involving service members under the Uniform Code of Military Justice (UCMJ). These activities are not considered a violation of the PCA. 

Federalization of the National Guard

When the National Guard is federalized, it falls under Title 10 authority and becomes subject to the PCA. However, when operating under state control (Title 32 or State Active Duty), Guardsmen are not bound by PCA military restrictions. 

Why The PCA Matters in Military Law

The PCA serves as a guardrail for maintaining the civil-military balance in a democratic society. It ensures that military forces do not overstep their constitutional role, preserving the distinction between law enforcement and warfighting. 

From a legal perspective, the PCA exists at an intersection of various elements of military law:

• Operational Boundaries: Commanders must ensure compliance with PCA when deploying troops for domestic missions. 
• Use of Force Guidelines: Military personnel must receive clear rules of engagement that reflect the legal limits imposed by the PCA. 
• Legal Oversight: Judge Advocate General (JAG) officers often review planned missions for potential PCA violations. 

Violations of the PCA can lead to public outcry, legal scrutiny, and disciplinary action. 

In the military justice system, unlawful orders that contravene the PCA are subject to challenge, creating a critical need for proper education and training among officers and enlisted personnel. 

Implications for Service Members

A key question many service members have is: What happens if a service member is ordered to violate the Posse Comitatus Act?

The answer lies with the UCMJ. Specifically, Article 92: Failure to Obey an Order or Regulation outlines the responsibilities of service members in regards to the PCA. 

Under this article, service members are required to obey lawful orders. An order that contravenes a federal law like the PCA is considered unlawful. As a result, service members have a legal duty not to comply. 

However, this creates a dilemma. Refusing an order that appears unlawful may itself result in disciplinary action unless the refusal can be justified and proven.

In these cases, service members are advised to:

• Seek clarification through the chain of command
• Request legal counsel
• Document the citation if there is a reasonable belief that the order is illegal 

Knowingly participating in a PCA violation could lead to:

• Administrative actions (reprimands, demotions)
• Judicial punishment under the UCMJ
• Potential civilian prosecution (exceedingly rare)

 

In practice, higher command levels are typically responsible for interpreting the legality of domestic missions. However, every service member bears individual responsibility for their actions as per their oath to uphold the Constitution. 

Does Posse Comitatus Apply to the National Guard?

The National Guard occupies a unique legal space when it comes to the PCA. So, does Posse Comitatus apply to the National Guard? Its status depends on the authority under which it is operating:

State Active Duty (SAD) and Title 32 Status

When the National Guard troops are under state control, commanded by a state governor, they are not subject to the PCA. This allows governors to use their guard forces for law enforcement during emergencies such as natural disasters, civil unrest, or public health crises.

Examples of SAD:

• Guard troops assisting during Hurricane Katrina (2005)
• Deployment of troops during the COVID-19 response
• Civil unrest missions (2020 protests)

As you can see, National Guard mobilizations typically occur under state authority, granting them the right to enforce domestic law. Only when they become federalized is the Guard beholden to the PCA. 

Title 10 Federal Activation

When the National Guard is federalized, it becomes part of the active-duty military and is thus subject to the PCA. Once under federal command, their authority to conduct law enforcement activities is restricted unless Congress or the President authorizes it through an exception, such as the Insurrection Act. 

Therefore, the National Guard’s flexibility makes it a preferred force for domestic missions, often bridging the gap between federal authority and state needs. 

However, it is still the duty of every National Guard member to hold themselves and their superiors accountable for following the PCA. 

Contact Daniel Conway & Associates for Any Questions About the PCA

If you’re a service member facing questions about lawful orders, military jurisdiction, or the implications of Posse Comitatus, it’s critical to have experienced legal guidance on your side. 

Daniel Conway & Associates is a trusted military defense law firm with a proven record defending service members under the Uniform Code of Military Justice. 

Visit our website to schedule a confidential consultation. Discover how our team can safeguard your rights, rank, and future, both in and out of the military. When your career is on the line, rely on the team of experienced lawyers that understands the UCMJ and PCA inside and out. 

Contact Daniel Conway & Associates today!