In early October, following the mass shooting at Oregon’s Umpqua Community College, Republican presidential candidate Ben Carson shared some of his views on gun policy during an interview with CNN. At one point, his comments turned to the historical. “I think the likelihood of Hitler being able to accomplish his goals,” he said, “would have been greatly diminished if the people had been armed.”

Carson’s soundbite is a version of a theory forwarded by the National Rifle Association and its surrogates since at least the 1960s. In this reading of world events, Third Reich-era gun laws in Nazi-occupied Europe made the Jews defenseless against ghettoization, and ultimately genocide. But it’s a thesis that’s been disproven for almost as long as it’s been in circulation.

Indeed, the gun-control-hastened-the-Holocaust argument was officially invalidated in a report presented during a July 1968 Senate Judiciary subcommittee debate over the Firearms Registration and Licensing Act. In his drive to create licensing requirements that would keep guns out of the hands of criminals and chronic substance abusers, the bill’s sponsor, Senator Joseph Tydings of Maryland, set out to refute what was already a popular NRA talking point: “No dictatorship has ever been imposed on a nation of free men who have not been first required to register their privately owned weapons.”

One of the persons giving testimony during the hearing was John Dingell, then early into his long run as a Democratic Representative from Michigan. He also happened to be a member of the NRA’s Executive Committee (he would later establish its lobbying arm). While debating the efficacy of New York City’s handgun licensing law in reducing crime, Dingell said, “We have here the same situation we saw in small degree in Nazi Germany. There they did not prohibit citizens from having guns. All they said was first of all we want to register them, and we are going to stop crime by it.”

Tydings became agitated and demanded that Dingell back up his claim with facts “other than from the NRA.” A heated exchange followed, with Tydings telling Dingell, “This is an argument extremists use.” Then Tydings played what he saw as his trump card, presenting a report he’d commissioned the previous August from the Library of Congress’s Legislative Research Service. The book-length document examined gun laws in Nazi-occupied Germany, Italy, France, and Austria during World War II.

In analyzing four European countries, the authors of the report concluded they could make “no positive correlation between gun laws and dictatorships.”

Here’s the document in full, courtesy of the Library of Congress:

“One may reasonably assume that if gun registration laws constituted a primary factor in the rise of dictatorships, these countries would have since revised their laws to prevent future dictatorships,” the report’s authors state. “This has not been the case. The four countries today have substantially the same gun laws as those in force prior to the advent of dictatorship.”

As for the origin of the popular NRA talking point that launched all this research — “No dictatorship has ever been imposed on a nation of free men who have not been first required to register their privately owned weapons” — one of its first appearances seems to come in The John Franklin Letters, an epistolary novel published in 1959. Set in the early 1970s, the book spins a tale of a liberal, Big Brother-esque government that forces Americans into economic serfdom, and closes with the swearing-in of a black president.