Earlier this week, Senators Elizabeth Warren and Richard Blumenthal, both members of the Senate’s Armed Services Committee, urged President Biden to issue a policy directive to prohibit the unlawful mobilization of our military against Americans.

The letter explains that a long-standing law prohibits any part of the Armed Forces from executing the law absent Constitutional or Congressional authorization. Senators Warren and Blumenthal emphasized that the only exception to this law is a narrow one, limited to “insurrection, rebellion, or extreme civil unrest,” and the Department of Defense has instructed its commanders to limit any mobilization under this exception to be limited to emergencies and to move as quickly as possible back to civil responsibility for military operations.

These long-standing laws—and the idea that our military should not be mobilized against Americans—are cornerstones of our democracy and indeed any functioning democracy. But Trump appears poised to turn the military against Americans and against immigrants within U.S. cities. In October, Trump told a Fox News reporter that he would be willing to use the military against enemies “from within” and “radically left lunatics” on Election Day. And he has confirmed that he plans to baselessly declare a national emergency as a tactic to militarize mass deportations—in other words, to abuse his power to overrule functioning local governments and turn the military against U.S. cities. His threats to order unlawful military efforts would place our military in an untenable position, undermine local and state governments, and harm U.S. citizens and residents. And he takes these acts knowing that a corrupt, unduly influenced Supreme Court has already granted him unprecedented and broad presidential immunity for official acts, regardless of how overtly unlawful those acts are.

Our service men and women should not be ordered into active conflict with U.S. citizens absent narrow and extreme circumstances—and certainly not on the whim of a President seeking to silence opposition, cripple local governments, or deport immigrants.  Senators Warren and Blumenthal are requesting a reasonable policy directive that will protect our civil liberties, clarify the appropriately judicious manner in which the President should consider military mobilization, and restrain unlawful presidential overreach.