Dallas police chief David Brown stated the obvious on Monday when he said open-carry laws make it harder for law enforcement to do its job.

“It is increasingly challenging when people have AR-15s slung over and shootings occur in a crowd,” Brown said, referring to a type of rifle that is commonly used in mass shootings.

And they begin running and we don’t know if they are a shooter or not. We don’t know who the ‘good guy’ versus who the ‘bad guy’ is if everybody starts shooting.

No doubt conservatives and gun owners, who only days ago praised Brown and his department for the way they ended a mass shooting of police officers in the Texan city, will take issue with his statement.

They argue that the only thing that stops a bad guy with a gun is a good guy with a gun.

But that is only true when the good guy is a cop.

Rare

The Washington Post has reported that armed civilians seldom stop a criminal with a gun. It happens, but it is no way measures up to the prevalence of gun crime in America.

The same newspaper found that for every instant in which a gun is used to kill a criminal in self-defense, 34 innocent people die in gun violence.

The idea that armed citizens provide a first line of defense is simply not borne out by the facts.

The FBI reported in 2014 that only seven out of the 160 mass shootings that took place between 2000 and 2013 ended when a civilian came to the rescue. And four of those were private security guards.

When amateurs insert themselves in a gunfight, the result is more often confusion.

That’s what Brown saw in Dallas last week, when his officers mistakingly assumed there were multiple shooters just because there were so many guns around.

Not normal

It’s not normal for people to carry rifles around in public.

If you’re about to walk into a store and see someone carrying an AR-15 on their back going in before you, do you still go in?

I wouldn’t. I can’t tell if it’s a “good guy” or a “bad guy,” but I do know that the chances of me being shot when there’s a gun in the room go up considerably, so why risk it?

That’s the pernicious effect of open-carry laws. They force everyone who means no harm to be more mindful and suspicious (including “good guys” with a gun, who must be careful they’re not mistaken for criminals) and make it easier for people who do mean harm to get closer to their targets.