What is the primary purpose of the Posse Comitatus Act?

The primary purpose of the Posse Comitatus Act is to restrict the use of military personnel for domestic enforcement. This legislation, enacted in 1878, was designed to limit the role of the federal military in civilian affairs, specifically to ensure that the military would not be used to enforce domestic laws or suppress civil unrest unless explicitly authorized by law.

By prohibiting military involvement in civilian law enforcement duties, the Act underscores the importance of maintaining a clear separation between military and civilian roles, thereby protecting citizens' civil liberties and preventing potential abuses of power by the military. The intent is to ensure that law enforcement remains the responsibility of civilian authorities, maintaining the principle of civilian control over the military.

In connection to the other provided choices, it is clear that while state laws and the concept of a federal police force may relate to law enforcement, they do not capture the essence of the Posse Comitatus Act, which specifically focuses on the limitations of military power in domestic settings. Additionally, while regulating the militia touches on military concerns, the Act's specific focus is on military personnel's engagement in law enforcement rather than militia regulation.