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The Posse Comitatus Act Explained
The law generally prevents the president from using the military as a domestic police force.
It finds expression in the Constitution’s division of power over the military between Congress and the president, and in the guarantees of the Third, Fourth, Fifth, and Sixth Amendments, which were in part reactions to abuses committed by the British army against American colonists. This conclusion is consistent with the law’s legislative history, which suggests that its drafters chose to include the language about constitutional exceptions as part of a face-saving compromise, not because they believed any existed. In this way, the Trump administration brought a large, federally controlled military force into Washington and used it for civilian law enforcement, all while skipping over the procedures in the Insurrection Act and evading the political costs of invoking it.
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