President Donald Trump, fond of fomenting his supporters’ fears, has reportedly warned that a bad showing in this November’s midterms could lead to violence. A Democratic wave, he’s said to have told evangelical leaders in a closed-door meeting last week, will loose left-wing protestors to exact bloody retribution against their conservative foes.

However overheated, Trump’s prediction was in sync with the dark fantasies of some of his most extreme boosters. Anticipating an autumn of leftists running wild in the streets, a nationwide network of far-right militias was already preparing to mount an armed response. Which leaves state and local leaders, again, needing to plan for the possibility of uniformed men displaying AR-15s self-deploying to their towns, in search of trouble.

Late last month, the paramilitary association the Oath Keepers announced what it calls its “Spartan Training Group Program,” intended to quell the anti-Trump resistance with intimidation and, should things come to it, bullets. Among the skills the group is looking for in training camps attendees: experience with infantry tactics, sharpshooting, and small arms skills.

Oath Keepers founder Stewart Rhodes told the conspiracy website InfoWars that he envisions the program bolstering his ranks for the express purpose of going head-to-head with antifa and other left-wing protestors, essentially promising repeats of the fatal clashes at last August’s Unite the Right rally in Charlottesville, Virginia. Rhodes anticipates Spartans engaging with protesters as his Oath Keepers did during the 2015 anti-police brutality protests in Ferguson, Missouri, which “was probably where we were closest to using lethal force.” He foresees his trainees acting at the direction of sheriffs, governors, or the president. Or, he added, they could go to protests on their own, to look for disruptions to put down.

It may all be just bluster, but recent precedent shows militias engaged in just such confrontations. Armed far-right militant groups like the Three Percenters and Proud Boys have gotten into street fights with leftists through this summer. Rhodes is intimating more of the same.

For cities and towns that prefer to leave peace-keeping to their police forces, rather than ideologically motivated interlopers, the latest resurgence of the militia movement appears to present a bind. The open carry of guns is legal in all but five states; most states also have laws prohibiting local restrictions on firearms, including banning the weapons from protests.

But experts on the militant far-right stress that state and local authorities do have options — options that are actually strengthened by the militias’ stated intention of battling political enemies.

Mary McCord is a Georgetown University Law School fellow and former Department of Justice prosecutor who worked with Charlottesville to sue organized demonstrators and counter-protesters who fought it out on the city’s streets last year. Her court fight has been successful, so far. She has secured consent agreements from Unite The Right organizers and attendees not to return to the city as armed groups.

After watching Rhodes’s Infowars interview, she was disturbed.

“This is pretty awful,” she said. “When you have armed groups acting in a coordinated manner but without any public accountability, that’s dangerous.”

With her Georgetown colleagues, McCord has dug into what states can do to stop groups like the Oath Keepers from prepping for and participating in public disturbances. She found that 28 states have criminal statutes that forbid drilling and parading in public with firearms, which the law recognizes as distinct from open carry by individual gun owners. Twenty-five states have anti-paramilitary activity statutes that prohibit group training in firearms or explosives in furtherance of civil disturbance.

McCord said that if local governments or prosecutors can prove that groups like the Oath Keepers “plan on training to stand with AR-15s to protect neo-Nazis during demonstrations that have every expectation of turning into violent melees,” the authorities might be able to prove in court that the groups were violating the law “just by having training camps. “

Rhodes’s own statements alone could provide that proof, McCord said. When Rhodes says he wants to fight “antifa and the far left,” he indicates that “these people intend to use these training camps to prepare for participating in civil disorder.” McCord said she has consulted with Murfreesboro and Shelbyville in Tennessee and Newnan, Georgia, about using the laws described above to stop armed militias from filling their streets.

Kathleen Belew, a historian at the University of Chicago, has studied some of the same arcane – but newly relevant – laws. “A lot of places have laws against parading in public with firearms, and anti-Klan laws against going in disguise on the public highway,” she said. “In Texas, they have a law prohibiting parading in public or creating an army that is not under the government’s direct control.”

In her book Bring The War Home, Belew documented the paramilitary turn of white power groups from the 1970s through the 1990s. She notes that right-wing groups have always presented a much more dangerous threat than left-wing groups, however radical. Indeed, according to a report released last year by the Government Accountability Office, far-right extremist have committed more acts of deadly violence since 9/11 than those of any other ideology. Left-wing extremists were responsible for the fewest.

“The ‘violent left’ has never been anywhere near as well armed or trained as the ‘violent right,’” Belew said. “The confrontation of those two sides is not an equal clash between two violent groups.”

Radical left-wing protest groups have been favorite targets of far-right extremists for decades. Belew pointed to a 1979 incident in North Carolina, when neo-Nazis and Klan members armed with assault weapons attacked a Communist demonstration in the city of Greensboro, killing five leftists and injuring more than a dozen.

“Many things that seem new are not new,” Belew said. “The idea of paramilitary training and confronting a violent left appear throughout the earlier white power movement.”

Belew observed that criminal prosecutions of paramilitary groups like those that attacked the Greensboro Communists often fail. Indeed, the attackers in that case were acquitted in both state and federal court by arguing they acted in self-defense, and were motivated out of political animus rather than racial hatred. By contrast, civil anti-paramilitary statues have a proven track record of disrupting extremist organizations, and are constitutional to boot.

Where McCord has mined law texts to build a legal playbook for places concerned about having their public safety usurped, Belew has also analyzed the circumstances that may be required to compel municipal officials to use the authority conveyed by dusty statutes. In the past, enforcement has rarely happened without a push from activists, she notes. Belew points to the example of the Southern Poverty Law Center’s 1981 lawsuit on behalf of Vietnamese fishermen in Texas who were harassed by a Klan group that had set up training camps. Lawyers at the nonprofit shut down Klan operations when they got a federal judge to issue an injunction against their training operation.

Civil suits brought by individuals or activists “have been successful because they can prohibit association, seize firearms, and other assets so that these groups are hamstrung,” Belew said. Through its case against the Klan in Texas, the SPLC got a copy of the racist group’s member rolls. With the information, the SPLC could petition the court to prohibit members of the Klan from associating with one another. That inhibited the bigots’ ability to not only intimidate racial minorities, but also to grow as a social movement.

There is one limitation to the approach that McCord and Belew prescribe: some local right-wing governments might welcome the head-cracking services of groups like the Oath Keepers.

“If [a far-right group] goes to the governor to get permission to set up training camps, and the governor authorized it to report directly to him, that would be constitutional,” McCord said.

In the Trump era, such a prospect is only slightly far-fetched. Last year, The Trace found that multiple elected Republicans and party figures at the local level have joined forces with militia chapters.