Deploying National Guard troops into Chicago against the wishes of Gov. JB Pritzker and other elected officials here amounts to a “break-glass-in-case-of-emergency thing to do.”

And “nobody’s suggesting there’s an emergency.”

That, in a nutshell, was the take from three legal scholars who spoke Tuesday to the Chicago Sun-Times after President Donald Trump said he might deploy troops to a city he called a “killing field” even though homicides are down.

The lack of any emergency could be a key difference between a National Guard deployment here and what happened in California last June. Trump sent troops into Los Angeles amid reports of violence, prompting an ongoing legal battle with California Gov. Gavin Newsom.

Now, Illinois officials say they’re scrutinizing the California lawsuit while waiting to see what Trump does next — and what authority he claims if he follows through on his threat. He’s hedged on the idea more than once.

The experts who spoke to the Sun-Times discussed the California case and the archaic laws at play there. But they also put down their law books for a moment to discuss the United States’ founding principles — and to lay out the risks of a military deployment for the country.

“It’s very important to understand that this is not how we do things in the United States,” Joseph Nunn, counsel at the non-partisan Brennan Center for Justice, said. “Americans have been — since the founding — extraordinarily suspicious, and rightly so, of domestic [use] of the military.”

Dan Maurer, an associate professor of law at Ohio Northern University and a retired Army JAG officer, said Trump risks sending soldiers on a mission that they’re “not well trained to handle” if he follows through on deployment in Chicago.

“That’s just not morally right, not fair, and certainly not justifiable,” Maurer said.

And Justin Levitt, the Loyola Marymount University law professor who applied the “break-glass-in-case-of-emergency” label to the situation, said what happens next might just depend on “how much the courts allow themselves to see what’s really going on.”

A ‘highly deferential’ court ruling

A clash between protesters and immigration authorities prompted Trump’s deployment of 2,000 California National Guard troops to Los Angeles last June. Newsom quickly responded with a federal lawsuit that’s still being hashed out in the courts.

The lawsuit acknowledged examples of people “breaking the law and acting violently.” But it denied that a rebellion or insurrection had broken out at any point.

The White House did not invoke the Insurrection Act when it sent troops into Los Angeles, though. That law is known as one of the key exceptions to the Posse Comitatus Act, which generally prohibits federal troops from engaging in civilian law enforcement except when authorized by law.

Instead, Trump cited a law allowing the president to call into federal service members of the National Guard of any state if there is an invasion or rebellion — or if the president is “unable with the regular forces to execute the laws of the United States.”

Justice Department lawyers also explained that troops were not sent to Los Angeles to engage in law enforcement. Rather, they were there to protect law enforcement officers.

A lower-court judge initially sided with Newsom. The judge was quickly blocked by the 9th U.S. Circuit Court of Appeals, though. It found courts had a role to play in reviewing Trump’s decision-making. But it also concluded they must be “highly deferential” to the president on the matter.

The 9th Circuit pointed to evidence that protesters “significantly impeded” the execution of federal law by throwing objects at ICE vehicles and “concrete chunks, bottles of liquid, and other objects” at officers, and also by using “large rolling commercial dumpsters as a battering ram.”

The court then found Trump “likely acted within his authority” to send the troops into Los Angeles. In doing so, it blocked a temporary restraining order against Trump’s deployment.

A bench trial has since played out back in the lower court this month, with no ruling yet from the judge.

Levitt on Tuesday argued there’s some nuance in the 9th Circuit’s ruling, though. He said the court only found “plausible” the idea that federal law enforcement had been impeded by the protesters — not that the claim was correct.

Put more simply, Levitt said the court considered whether it’s “at all plausible that someone might think that it’s raining outside.” It didn’t determine if it was actually raining.

“I think they found that there was enough water on the window that someone might possibly, plausibly have thought it was raining outside,” Levitt said. “Even if that water came from somebody’s sprinkler and not the sky.”

Meanwhile, in Chicago, he said “you look out the window and it’s mostly sunny and partly cloudy, but mostly sunny.”

‘States may not invade one another’

Levitt and his colleagues had a darker take on speculation that Republican governors might set out to help the president by mobilizing troops on their own to assist a federal mission in Illinois.

Pritzker acknowledged this concern during a press conference Monday.

“To my fellow governors across the nation who would consider pulling your National Guard from their duties at home to come into my state against the wishes of its elected representatives and its people,” he said, “you would be failing your constituents and your country.”

“Cooperation and coordination between our states is vital to the fabric of our nation, and it benefits us all,” Pritzker added. “Any action undercutting that and violating the sacred sovereignty of our state to cater to the ego of a dictator will be responded to.”

If Trump were to federalize another state’s National Guard and send it to Chicago, the same laws would be in play as if he federalized the troops in Illinois, the experts said.

But another governor might cross a very bright line by choosing to send troops to Illinois on their own orders, in a bid to help Trump.

“Simply put,” Nunn said, “U.S. states may not invade one another.”

Pitting so-called red states and blue states against each other “is not a path we want to go down,” he added.

“I think it is dangerous,” he said. “I think it is destructive of military morale and discipline.”

And Maurer said the idea of a president using one state’s National Guard against the will of another “sounds a lot like what happened in the Civil War.”

‘No actual good reason’

Pritzker has promised to see Trump “in court” if the president deploys the National Guard to Chicago. But Illinois officials have few legal options until Trump actually sends in the troops.

For now, Illinois leaders are putting on a united front, insisting there is no emergency here and no need for the National Guard. Pritzker, Chicago Mayor Brandon Johnson, U.S. Sens. Dick Durbin and Tammy Duckworth and Illinois Attorney General Kwame Raoul were among several to come together for a massive downtown news conference on Monday.

While the White House has pointed to Chicago’s high murder rate, Pritzker and others note that the homicide rate has actually dropped by 30% compared to last year.

If Trump chooses to deploy National Guard troops for the purposes he’s described, Maurer said Trump would have to invoke the Insurrection Act. Like the law used in California, it has certain triggers that would need to be cited. He said Trump might also need to issue a proclamation to “immediately order the insurgents to disperse.”

But Maurer said Trump “absolutely has no basis for doing so in a place like Chicago.”

In fact, Levitt said that “everybody understands that there is absolutely no reason to deploy the National Guard in Illinois right now.” He said he doesn’t even think it’s a “seriously contested” issue.

“You don’t have to be a statistician, and you don’t have to be a lawyer [to] know instantly that there is no actual good reason to send the Guard into Illinois,” Levitt said.

“And that, I think, is the most important point.”