The American Civil Liberties Union caused some double takes last Sunday with a tweet blaming racism and “anti-Blackness” for the presence of the Second Amendment in the Constitution. It was jarring to see the ACLU, once an indomitable champion of the Bill of Rights, endorse the revisionist view that one of its core components, the right to keep and bear arms, exists for malevolent racial reasons.

That view is associated with Emory University historian Carol Anderson, who claims that the motivation behind the Second Amendment was the insistence by Southern whites on having access to the weapons they might need to quell slave revolts. It’s an interpretation other scholars find dubious. Harvard law professor Randall Kennedy, a leading authority on race relations, civil liberties, and US law, wrote recently that Anderson’s argument is made “unconvincingly, in the face of formidable scholarship to the contrary.”

In any case, the real racism associated with the Second Amendment isn’t in the rights of gun ownership that the Bill of Rights cemented into the Constitution’s text. It is in the long and shameful record of those rights being denied.

“For much of American history, gun-control measures, like many other laws, were used to oppress African Americans,” Adam Winkler, a constitutional scholar at UCLA, has written. In blatant disregard of the Second Amendment’s guarantee, Southern states enacted laws prohibiting black people, enslaved and free alike, from owning firearms. A Florida statute enacted in 1825 empowered white citizen patrols to “enter into all Negro houses and suspected places,” search for weapons, and “lawfully seize and take away all such arms, weapons, and ammunition.” In 1831, the Maryland legislature passed a law banning free black residents from carrying arms. The Tennessee constitution — which had formerly guaranteed gun rights to “the freemen of this State” — was amended in 1834 to restrict those rights only to “the free white men of this State.”

All such laws were, of course, egregious violations of the Second Amendment. In fact, some prominent abolitionists, such as the brilliant Massachusetts lawyer Lysander Spooner, argued that ratification of the Second Amendment had made slavery itself unconstitutional. “This right of a man ‘to keep and bear arms,’ is a right palpably inconsistent with the idea of his being a slave,” wrote Spooner in 1860. The constitutional right to keep arms, he pointed out, “implies the constitutional right to use them, if need be, for the defense of one’s liberty or life.” The logic was unassailable, which is why slavery’s supporters went to such grotesque lengths to evade it. In Dred Scott v. Sandford, the Supreme Court got around the problem by ruling that black people didn’t count as US citizens. If they were, Chief Justice Roger Taney wrote, the Second Amendment “would give to persons of the negro race … the right … to keep and carry arms wherever they went.” To Taney, that was unthinkable.

After the Civil War, racists continued to use gun control as a tool of white supremacy. A common provision of the postwar Black Codes adopted by Southern states made it illegal for the freedmen to possess firearms. To enforce those laws, white men assembled posses to intimidate black communities in the South and ensure they weren’t armed. The most notorious of those gun-control posses called itself the Ku Klux Klan.

Conversely, defenders of equality throughout US history, both white and black, have understood the importance of gun rights to civil rights. During the original congressional debate over the Fourteenth Amendment, Michigan Senator Jacob Howard stressed the importance of protecting “the personal rights guaranteed and secured by the first eight amendments to the Constitution, such as … the right to keep and bear arms.” The Second Amendment was as indispensable to black liberty as the rest of the Bill of Rights. A favorite formulation of Frederick Douglass was that if black people were to be really free, “they must have the cartridge box, the jury box, and the ballot box to protect them.”

To the framers of the post-Civil War amendments, it was self-evident that the right of freed slaves to have guns for self-defense was essential to their full-fledged citizenship. “Between 1775 and 1866,” Yale law professor Akhil Reed Amar wrote in his acclaimed book on the Bill of Rights, “the poster boy of arms morphed from the Concord minuteman to the Carolina freedman.”

When Reconstruction died, and the long dark night of Jim Crow began, the right to keep and bear arms became even more vital to the preservation of black life and the quest for civil rights.

Ida B. Wells, a prominent journalist and civil rights pioneer who helped expose the horror of Southern lynchings, noted in 1892 that the only the time the intended victim of a lynching escaped was “when he had a gun and used it in self-defense. The lesson this teaches … is that a Winchester rifle should have a place of honor in every black home, and it should be used for that protection which the law refuses to give.”

Seven decades later, Malcolm X was making much the same point, and explicitly grounding it in the Second Amendment: With black lives going unprotected by federal and state governments, he said, “it is only intelligent and it’s only right that Negroes protect themselves, and I have encouraged them to buy a rifle and a shotgun, which according to the Constitution is legal.”

But even then, gun control laws too often negated what the Second Amendment guaranteed.

Martin Luther King Jr. was denied a permit to carry a gun for protection, even after his house was firebombed. King’s inability to exercise his Second Amendment rights, observes the National African American Gun Association in a brief to the Supreme Court, which will hear a Second Amendment case this fall, is “perhaps the most stark illustration” of how the failure to uphold the right to keep and bear arms has “played a role in the history of the civil rights movement.”

The National African American Gun Association, incidentally, has expanded rapidly since it was launched in 2015 with a single chapter in Atlanta. Today it numbers 127 chapters with more than 39,000 members. They regard the Second Amendment not as a racist relic but as a critical defense against violent racism and other threats. The soaring rate of gun ownership among black Americans is a reassuring sign that the Bill of Rights is alive and well and doing what it was designed for. Even if the ACLU, these days, seems unclear on the concept.

(Jeff Jacoby is a columnist for The Boston Globe).