When militia members and white supremacists descended on Charlottesville, Va., last Saturday with Nazi flags and racist placards, many of them also carried firearms openly, including semiautomatic weapons. They came to intimidate and terrify protesters and the police. If you read reports of the physical attacks they abetted, apparently their plan worked.

They might try to rationalize their conduct as protected by the First and Second Amendments, but let’s not be fooled. Those who came to Charlottesville openly carrying firearms were neither conveying a nonviolent political message, nor engaged in self-defense nor protecting hearth and home.

Plain and simple, public terror is not protected under the Constitution. That has been the case throughout history. And now is the time to look to that history and prohibit open carry, before the next Charlottesville.

Historically, lawmakers have deemed open carry a threat to public safety. Under English common law, a group of armed protesters constituted a riot, and some American colonies prohibited public carry specifically because it caused public terror. During Reconstruction, the military governments overseeing much of the South responded to racially motivated terror (including the murder of dozens of freedmen and Republicans at the 1866 Louisiana Constitutional Convention) by prohibiting public carry either generally or at political gatherings and polling places. Later, in 1886, a Supreme Court decision, Presser v. Illinois, upheld a law forbidding groups of men to “parade with arms in cities and towns unless authorized.” For states, such a law was “necessary to the public peace, safety and good order.”

https://www.nytimes.com/2017/08/17/opinion/open-carry-charlottesville.html