Which of the following best represents a limitation on federal military power?

The Posse Comitatus Act serves as a significant limitation on federal military power, particularly in the context of domestic law enforcement. Enacted in 1878, this legislation restricts the use of the U.S. Army and Air Force in domestic situations, thereby establishing a clear boundary between military authority and civilian law enforcement. The intent of the act is to prevent the military from acting as a police force within the United States, which helps to uphold the principle of civilian control over the military and maintains the integrity of the civil legal system.

In contrast, while the Uniform Code of Military Justice establishes the legal framework for the military justice system, it does not limit military power in the same way. The National Security Act primarily focuses on the organizational structure of the military and intelligence community, often enhancing military power rather than limiting it. The Military Commissions Act deals with the framework for military commissions to try unlawful combatants, which does not fundamentally act as a limitation on military power. Thus, the Posse Comitatus Act stands out as the most direct legislative restraint on how federal military forces can operate within the civilian realm.