For nearly 150 years, a core tenet of the U.S. military — enshrined in the Posse Comitatus Act — has been that American troops should not be used in domestic law enforcement, except in the most extreme circumstances and only when expressly authorized by Congress or the Constitution.
The 1878 law bars military personnel from making arrests, conducting searches, or seizing property. But most of the troops President Donald Trump has federalized have been limited to protecting federal property, including buildings and vehicles, and ensuring the safety of civilian law enforcement, in particular, personnel from Immigration and Customs Enforcement.
Trump’s authority to federalize troops is derived from Article II of the Constitution, which specifies that as commander in chief of the military, the president is also commander of state militias “when called into the actual Service of the United States.”
The question before the courts is under what conditions can the president deploy troops domestically — whether Guard or active duty forces — against the wishes of a state governor, which by precedent generally requires civil disorder that is beyond the capability of state law enforcement to handle.
Already, two federal judges have ruled Trump has exceeded his constitutional authority in federalizing the California National Guard to patrol Los Angeles and, more recently, in planning to send out-of-state troops to Portland, after an Oregon judge blocked his attempt to federalize the state National Guard.
Trump was found to be in direct violation of the Posse Comitatus Act by effectively “creating a national police force with [himself] as its chief,” wrote San Francisco-based federal district court Judge Charles Breyer in his Sept. 2 ruling.
Similarly, federal district court Judge Karin Immergut, a Portland-based Trump appointee, ruled Oct. 4 that the small protests in Oregon’s largest city did not qualify as a “rebellion” nor did they pose a “danger of a rebellion,” and called Trump’s rationale for federalizing troops “simply untethered to the facts.”
The Trump administration is confident the ruling will be overturned on appeal.
“I would note the administration won an identical case in the Ninth Circuit just a few months ago,” Stephen Miller, White House deputy chief of staff for policy, said in an interview on CNN. “Under federal law, Section Title 10 of the U.S. Code, the president has the authority anytime he believes federal resources are insufficient to federalize the National Guard to carry out a mission necessary for public safety.”
But, Miller noted, even if Trump were to lose the case at the Supreme Court, “there are also many other options the president has to deploy federal resources and assets under the U.S. military to Portland.”
One option would be the Insurrection Act of 1807, a law that grants the president wide discretion in determining when military forces are needed to suppress rebellion, quell domestic violence, or enforce federal laws.
“The Insurrection Act is the ultimate exception to the Posse Comitatus Act,” the Brennan Center for Justice wrote in a brief for reporters. “That law, last amended in the 1870s, gives presidents great power in an emergency.”
During his first term, furious that protesters demonstrating across from the White House were making him look “weak,” Trump wanted to invoke the measure to send 10,000 active-duty troops into the streets of Washington, D.C.
When Defense Secretary Mark Esper and Joint Chiefs Chairman Gen. Mark Milley strongly advised against it, Trump called them “f***ing losers,” according to Esper’s 2022 memoir, A Sacred Oath.
“Can’t you just shoot them in the legs or something?” Trump said, according to Esper.
This time around, there is no one in the White House pushing back on the idea of deploying thousands of active-duty troops into America’s major cities to help battle street crime and round up illegal aliens.
“We have an Insurrection Act for a reason,” Trump said earlier this month. “If I had to enact it, I’d do that. If people were being killed and courts were holding us up, or governors or mayors were holding us up, sure, I’d do that.”
Whether Trump can invoke the Insurrection Act under the current circumstances is for the courts to decide, but there is also a fundamental political question: Does America want to cast aside the time-honored principle that our apolitical military should fight foreign foes, not its own citizens on U.S. soil?
When Trump tells his top generals and admirals — as he did last month in a speech at Quantico Marine Corps Base — that America is under invasion from “the enemy from within,” in “unsafe cities,” run by “radical left Democrats,” and that he’s signed an executive order to create “quick reaction force” to “quell civil disturbances,” and that it’s going to be “a big thing” for military commanders to focus on in “dangerous cities” such as San Francisco, Chicago, New York, and Los Angeles, which he thinks should be used as “military training grounds,” he risks driving a wedge between the American people and the military,” says retired Maj. Gen. Randy Manner, a former acting vice chief of the National Guard Bureau.
“We don’t use the American military to watch Americans. That is not the objective. If there are issues relative to law enforcement, that’s what you use — appropriately trained police officers,” Manner said in an interview on NPR. “You do not use military with armed weapons and with armored vehicles. They are not trained in these types of skills, and we should never have American soldiers on American streets.”
Democrats say they don’t believe the dispatch of military forces — Guard or active-duty — is really about fighting crime or protecting life and property.
“This is something the president always wanted to do because he wants to own these cities,” former Chicago Mayor Rahm Emanuel said on CNN, where he is now a paid contributor.
“The Chicago Police Department is 12,000 officers … It doesn’t even add up,” he said. “Two hundred Guardsmen from Texas who don’t know any of the community or any of the residents of Chicago are not going to do anything on public safety, and they’re definitely not going to do anything on immigration efforts.”
Gov. JB Pritzker (D-IL) announced that the state would challenge the deployment of Texas Guard troops to Chicago in court.
“Donald Trump is using our service members as political props and as pawns in his illegal effort to militarize our nation’s cities,” Pritzker said.
“This escalation of violence is targeted and intentional, and premeditated. The Trump administration is following a playbook: cause chaos, create fear and confusion, make it seem like peaceful protesters are a mob, by firing gas pellets and teargas canisters at them,” Pritzker said. “Why? To create the pretext for invoking the Insurrection Act, so that he can send military troops to our city. He wants to justify and normalize the presence of armed soldiers under his direct command.”
Miller, who has called the Democratic Party “a domestic, extremist organization,” insists the National Guard troops are needed in Portland to protect ICE agents, who he said “have been subjected to over 100 nights of terrorist assault, doxing, murder threats, violent attack, and every other means imaginable to try to overturn the results of the last election through violence.”
“The number one and two items in the GOP platform in 2024 were to turn back the border invasion and carry out the largest deportation program in American history,” Miller said. “Since Inauguration Day, there’s been an orchestrated campaign of terrorism and violence against ICE officers.”
Gov. Tina Kotek (D-OR) says Trump’s desire to send troops to Portland, where anti-ICE protests have been confined to a one-block area in a city that covers about 145 square miles, is a gross overreaction.
“What is happening here is that the federal government — without real facts, and the court has said there are no facts on the ground to justify this — is talking about putting military troops in American cities,” Kotek said. “It is crossing a line. This is a threat to our democracy.”
CHICAGO HAS NO SOVEREIGN RIGHT TO ITS OWN IMMIGRATION POLICY
In her ruling temporarily blocking the deployment of military troops to Portland, Judge Immergut wrote, “This country has a longstanding and foundational tradition of resistance to government overreach, especially in the form of military intrusion into civil affairs. This historical tradition boils down to a simple proposition: this is a nation of Constitutional law, not martial law.”
“Our fellow citizens should be confident that the U.S. military will always carry out lawful orders,” retired Lt. Gen. Ben Hodges said in an appearance on CBS, while adding, “I guarantee you that no soldier wants to have to use force against the American people.”
