President Trump “is considering a proposal to mobilize as many as 100,000 National Guard troops to round up unauthorized immigrants, including millions living nowhere near the Mexico border,” according to the Associated Press. White House press secretary Sean Spicer denies this report.
Should Trump attempt to use military personnel to enforce domestic immigration law, he is likely to encounter stiff legal resistance. The rules for National Guard members, however, are somewhat less restrictive and may allow Trump to implement this plan — but only in states where the governor supports his efforts.
The Posse Comitatus Act forbids the use of Army or Air Force personnel “as a posse comitatus or otherwise to execute the laws” except “in cases and under circumstances expressly authorized by the Constitution or Act of Congress.” Current law does permit the military to provide certain forms of support, such as “maintenance and operation of equipment” for federal immigration agents, but it does not permit direct military involvement in most law enforcement.
One provision of federal law, for example, requires the Department of Defense (DOD) to promulgate regulations to prevent “direct participation by a member of the Army, Navy, Air Force, or Marine Corps in a search, seizure, arrest, or other similar activity unless participation in such activity by such member is otherwise authorized by law.”
Accordingly, DOD issued a directive which “prohibits the following forms of direct assistance: (1) interdiction of a vehicle, vessel, aircraft, or other similar activity; (2) a search or seizure; (3) an arrest, apprehension, stop and frisk, or similar activity; and (4) use of military personnel in the pursuit of individuals, or as undercover agents, informants, investigators, or interrogators.”
So those are the rules governing U.S. military personnel. The rules governing the National Guard are a bit hazier because, as a 2013 report by the Congressional Research Service explains, “the National Guard is a military force that is shared by the states and the federal government.” As a general rule, when National Guard personnel operate under the control of the president, they are subject to the Posse Comitatus Act. When they operate under the control of a state governor, however, they are not subject to the act.
For this reason, one of the most important maps governing the future of civil liberties in this country may be this one:
That’s a map showing states with Democratic governors in blue and states with Republican governors in red. In the blue states, governors are more likely to resist Trump’s efforts to enlist the National Guard as immigration enforcers. In the red states, governors are likely to be more inclined to cooperate.
There are precedents for National Guard personnel being deployed to support federal Border Patrol officers. In 2006, for example, President George W. Bush “announced the deployment of up to 6,000 National Guard troops along the southern border” as part of a mission called “Operation Jump Start.” These troops, however, “remained under the control of the respective governors.”