Posse Comitatus Act (1878)

1) Link to the Text of the Act
Read the statute (18 U.S.C. § 1385)

2) Why It Was Done
Enacted after Reconstruction to limit the use of the U.S. Army in domestic law enforcement. It reinforced the separation between military and civilian authority.

3) Pre-existing Law or Constitutional Rights
The Constitution already divides civil and military powers, but before this law, federal troops were frequently used to enforce laws and support Reconstruction governments. This Act codified stricter limits.