The story so far: Widespread protests have erupted in Los Angeles, California, after raids by U.S. Immigration and Customs Enforcement (ICE) led to dozens of arrests. In response, U.S. President Donald Trump has deployed about 4,000 national guard troops and 700 marines.
Military troops, including national guard units, are barred from civilian law enforcement under the Posse Comitatus Act (1878), unless explicitly authorised by the Constitution or an Act of Congress. Such authorisation is provided through the Insurrection Act which permits the President to deploy the military during civil unrest. This can be done at a State’s request, or unilaterally to enforce federal law, suppress rebellion, or protect civil rights when a State government is unwilling or unable to act.
