Apologists for 17-year-old Kyle Rittenhouse, who is charged with murder after shooting two protesters in Kenosha, Wis., claim that the Second Amendment gives groups of individuals a right to gear up with lethal weapons and patrol not only their own streets but the streets of distant cities; Rittenhouse traveled 20 miles from his home in a self-described quest to protect property and render first aid. “If the cops aren’t going to stop them from throwing pipe bombs on innocent civilians, somebody has to,” an anonymous armed man in Kenosha told a Washington Post reporter. (There have been no reports of pipe bomb attacks.)

Nothing about the Second Amendment protects armed vigilantism. U.S. history is marked by efforts to control private armed groups, not unleash them. As Georgetown Law School professor Mary B. McCord pointed out in a letter to Kenosha’s mayor and other local officials, all 50 states forbid private paramilitaries. Wisconsin specifically prohibits such groups from acting as law enforcement.

Unfortunately, a combination of gun politics, permissive gun laws and social media has made these regulations relatively easy to evade. As a nation, we’ve blundered into a situation in which an armed mob can converge on an area, escalate tensions, even start shooting — and police can do little to stop it.

In 2008, in District of Columbia v. Heller, the Supreme Court held for the first time that individuals have rights to keep and bear arms for personal, non-militia uses. Advocates for armed private groups say this decision confirms their right to patrol towns like Kenosha. But, as revolutionary and expansive as Heller was, it’s not clear that it goes as far as these groups believe.

Justice Antonin Scalia, who wrote the majority opinion in Heller, was the chief proponent of a form of constitutional interpretation called “originalism.” Originalists believe that the limits of the Second Amendment are based largely on the Anglo-American tradition governing firearms: regulations found in English history or long American custom. And that tradition consistently viewed private armed groups as threats to public peace, not its guardians.

In the 14th century, King Edward III barred armed men from coming to “Fairs, Markets, [or] in the presence of the Justices or other Ministers” upon pain of imprisonment. More than a century later, King Henry VII prohibited quarreling gentry from leading armed retainers into the city square. In 1604, the English jurist Lord Coke, famous for establishing the principle that “a man’s home is his castle,” also said a man could not assemble an armed retinue to protect him in town.

Early American lawmakers copied these English restrictions into their legal treatises and guidebooks, sometimes verbatim. American manuals for justices of the peace instructed law enforcement to apprehend those going “among any great Concourse of People” with offensive weapons. Shortly after the Civil War, when the progenitors of the Ku Klux Klan began to appear in the streets, a Union general prohibited private “organizations of white or colored persons bearing arms” from assembling, patrolling or making arrests, because official law enforcement alone possessed that power. In 1886, in Presser v. State of Illinois, the Supreme Court held that the state could prevent socialist labor organizers from parading armed in the streets of Chicago. The prohibition, according to the court, did “not infringe the right of the people to keep and bear arms.”

Armed peacekeeping by private groups was outlawed in the 20th century, too. States like Washington banned private armies after plutocrats started using them to quell labor unrest. In 1907, Washington’s highest court upheld a conviction under such a law, stating, “Armed bodies of men are a menace to the public, their mere presence is fraught with danger, and the state has wisely reserved to itself the right to organize, maintain and employ them.” As governor of California in 1967, Ronald Reagan signed a law criminalizing armed patrols after the Black Panther Party for Self-Defense deployed riflemen in Oakland and staged an armed march in Sacramento. He said there was “no reason … a citizen should be carrying loaded weapons.”

The common purpose behind these long-standing regulations is apparent: When private groups go about a city armed, others arm themselves in response, escalating tension — along with the risk of injury and death. So what changed to make it routine, today, for armed individuals to descend upon places like Kenosha purporting to act as law enforcement, with deadly consequences? Three interrelated factors appear to be at work.

First, the politics of the Second Amendment have outpaced the law of the Second Amendment. The court held in Heller that an individual had a right to possess a firearm in his home and did not have to be a member of the organized militia (namely, the National Guard) to do so: That was the extent of the ruling. Heller did not specify when, if ever, an individual has a right to carry a gun off his property or explain what role, if any, the organized militia serves in regulating public guns. In the 12 years since Heller, the court has not clarified these points. Gun rights activists have interpreted this silence — as well as some lower-court decisions favoring gun rights — to mean that the Second Amendment guarantees a right to carry a firearm anywhere in the United States in the company of others (meaning existing state laws banning this would be unconstitutional).

Second, in the past 20 years, Republican state legislatures, at the behest of the National Rifle Association, have enacted ever-looser regulations on public weapons (in Wisconsin, legally owned weapons may be carried openly or concealed) and the use of deadly force. Citizen’s arrest laws are a complicated patchwork but are particularly broad in some jurisdictions. In some states, a person can carry a firearm with absolutely no training on how to use it; in others, such as Florida, deadly force is presumed reasonable unless proved otherwise. Worse, legislatures have preempted local governments’ gun policies. As a result, groups may enter a city claiming to be guardians of the peace, with no training, no oversight and no political accountability, and in defiance of local leaders and community members. (In Kenosha, the signals were mixed, with the mayor suggesting that he wanted no armed outsiders on the streets even as police on the ground offered them thanks and water.)

Third, social media has made it easy to organize lots of people, in lots of places, very quickly and cheaply. The ease of coordination, combined with lax laws on public weaponry and Heller’s ambiguity, blurs the line between a prohibited private militia and a spontaneous gathering of gun owners. Even though these individuals must still meet the standard of justifiable self-defense if they use their firearms, the presence of armed, untrained people, in a highly confrontational atmosphere, surrounded by ambiguous provocations (exploding fireworks, paintball guns) creates a situation that can suddenly turn deadly.

Tolerance for heavily armed, self-appointed peacekeepers in our public square is not required by the Second Amendment. In volatile times like these, despite legitimate concerns about police violence, it’s better to entrust law enforcement to professionals accountable to the people — rather than to private groups accountable to no one.