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Last week Rep. Nancy Pelosi warned President Donald Trump that if he declared an "emergency" to build a wall, "think what a president with different values can present... Why don't you declare (the epidemic of gun violence in America) an emergency, Mr. President? I wish you would... A Democratic president can declare emergencies as well."

Her fellow Democrats Sen. Kamala Harris and Sen. Elizabeth Warren quickly agreed.

Warren tweeted: "Gun violence is an emergency. Climate change is an emergency..."

Yikes.

Not every problem in America should be declared an emergency -- or used by a president to justify acting without Congress.

But why are guns on the Democrats' "emergency" list anyway?

One reason is sloppy reporting by lazy media.

Last year, they claimed that there were school shootings at "hundreds of schools." It was "an almost daily occurrence" in the U.S., some said.

This was nonsense. NPR reporters looked into the 235 shootings reported by the U.S. Dept of Education and were only able to confirm 11 of them.

It turned out that schools were added to the list merely because someone at a school heard there may have been a shooting. Good for NPR for checking out the Education Department's claim.

Economist John Lott, president of the Crime Prevention Research Center (and father of one of my producers) spends much of his time researching gun use and correcting shoddy studies.

A few years ago, much of the media claimed that the U.S. has "the most mass shootings of any country in the world." President Barack Obama added it's "a pattern now that has no parallel anywhere else."

CNN and The L.A. Times wrote about "Why the U.S. Has the Most Mass Shootings." ("The United States has more guns.")

But the U.S. doesn't have the most mass shootings, says Lott. It's a myth created by University of Alabama associate professor Adam Lankford, a myth repeated by anti-gun media in hundreds of news stories.

"Lankford claimed that since 1966 there were 90 mass public shooters in the United States, more than any other country," says Lott. "Lankford claimed 'complete data' were available from 171 countries."

But how could that be? Many governments don't collect such data and even fewer have information from before the days of the internet.

A shooting in say, India, would likely be reported only in local newspapers, in a local dialect. How would Lankford ever find out about it? How did he collect his information? What languages did he search in?

He won't say.

"That's academic malpractice," says Lott in my video about the controversy.

I'm not surprised that Lankford didn't reply to Lott's emails. Lott is known as pro-gun. (He wrote the book "More Guns, Less Crime.") But Lankford also won't explain his data to me, The Washington Post or even his fellow gun control advocates.

When Lott's research center checked the data, using Lankford's own definition of a mass shooting, "four or more people killed," the center found 3,000 shootings around the world. Lankford claimed there were only 202.

Lankford said he excludes "sponsored terrorism" but does not define what he means by that. To be safe, Lott removed terrorism cases from his data. He still found 709 shootings -- more than triple the number Lankford reported.

It turns out that not only did the U.S. not have the most frequent mass shootings, it was number 62 on the list, lower than places like Norway, Finland and Switzerland.

There was also no relationship between the rate of gun ownership in different countries and the rate of mass shootings.

If journalists had just demanded Lankford explain his study methods before touting his results, his "more mass shootings" myth would never have spread.

So if Nancy Pelosi, Kamala Harris and Elizabeth Warren ever follow through on their threat to declare gun violence a "national emergency," be sure to check their math.

Or just remember the wisdom of the Second Amendment.

Government's desire to control us -- and to lie to make its case -- is the real emergency.