From the Brennan Center for Social Justice
Posse Comitatus Say What?

The Posse Comitatus Act bars federal troops from participating in civilian law enforcement except when expressly authorized by law. This 147-year-old law embodies an American tradition that sees military interference in civilian affairs as a threat to both democracy and personal liberty. However, recent events have revealed dangerous gaps in the law’s coverage that Congress must address. Click here for the truth, whole truth?