Last week’s announcement by the ACLU that it will no longer defend unpopular speech by heavily armed groups wasn’t just a betrayal of its historic mission. The group is a private non-profit organization, so it can choose its cases at will. But Americans trust the ACLU to articulate what the Constitution means, and when it claimed that the First Amendment itself doesn’t protect such groups, it betrayed the American people.

On Wednesday, in reaction to the recent march by hateful protesters in Charlottesville, Virginia, the largest ACLU chapters in California issued a statement, later backed up by the national group, that declared “if white supremacists march into our towns armed to the teeth and with the intent to harm people, they are not engaging in activity protected by the United States Constitution.”

“Intent to harm people?” That loophole could wipe out the whole concept of free expression. How does the ACLU know the intent of marchers? More importantly, how does the government discern which groups are intent on harm, and thus are ineligible for permits, and may even be arrested for the things they say?

Sure, the First Amendment only protects the right of individuals to “peaceably assemble,” but that only means that if they get violent they can be prosecuted – not that if they are considered likely to show up with weapons the government can intuit that they plan violence and thus withhold their rights.

America’s despicable white supremacist marchers might choose to bring along a firearm for lots of reasons beyond instigating violence. They may intend to scare off “antifa” or other hostile groups with a history of violence toward people like them, or perhaps they want to be ready to defend themselves if attacked. Just as important, carrying handguns in states (like Virginia) with open-carry laws may be an act of expression itself, taking a stand on the social controversy over such laws by publicly asserting their legal rights.

Therefore, it is impossible for the government determine the intent of a group that includes armed, even heavily armed, law-abiding participants. After all, if the government wishes, it can just make up stories of militarized marchers, which is what Virginia Gov. Terry McAuliffe did after Charlottesville. He spun a fantastical story about “80 percent of the people here” being armed with semiautomatic weapons, and told a podcast that “they had battering rams and we had picked up different weapons that they had stashed around the city.” Local police disputed those claims, saying instead that the marchers were significantly outgunned by law enforcement.

It’s preposterous to think that bringing a weapon to a rally automatically demonstrates an intent to cause violence, particularly because the weapon in the only civilian death in Charlottesville was … an automobile. Can the police now shut down protests if they determine that some of the marchers arrive “heavily armed” with SUVs and sedans?

And even if a group is determined to be violent, what about an individual who comes unarmed? Does she relinquish her right to express her ideas?

The Supreme Court has been clear that the “fighting words” exception to free speech is exceedingly narrow and applies only to speech “likely to cause imminent lawless action” – speech that will probably provoke opponents to attack. Carrying guns does not make violent reaction to the speech more likely – it makes it less likely, because the people being offended don’t want to get hurt and are smart enough to restrain themselves.

Look, the origin of the ACLU’s now-reduced commitment to defending unpopular speech is no mystery. In the age of Trump, liberal-minded Americans who appreciated the group’s opposition to the president on issues like immigration, health care, and transgender rights joined the group in droves. Since the election, ACLU membership more than quadrupled, and the group raised nearly $80 million from more than a million donors in the first four months after the election alone.

But many of those new supporters expected the American Civil Liberties Union to lead the liberal charge against the president, not understanding that the group justifies most of its liberal policies (however shakily) in the context of, well, civil liberties. (The ACLU encouraged that misimpression in some of its fundraising.)

So they were furious when they heard the group had sued the city of Charlottesville to ensure the white supremacist rally could be held downtown near the statue they wanted removed, instead of in a different park a mile away. By limiting its support for unpopular speech to to unarmed groups, the ACLU has tried to please its new members while maintaining its historic mission.

Again, they’re a private group so that’s their right. And they could have legitimately said, “Our members don’t want us to defend hateful bigots” or even “We disagree with the current broad interpretation of the First Amendment and think armed groups forfeit their freedom to assemble.” But instead they misrepresented the Constitution, which should offend freedom-loving Americans.

As a conservative, I like some of what the ACLU advocates but disagree with most of it. My liberal friends tend to have the opposite opinion of their agenda. But it would be a tragedy for America were the ACLU to become just another liberal (or conservative) organization. In a free society, smart decisions result from passionate conversations between people with different priorities. We need an unflinching voice of loyalty to our First Freedoms, and this week, sadly, we may have lost the only real one we had.

David Benkof is a columnist for The Daily Caller. Follow him on Twitter (@DavidBenkof) or Facebook, or E-mail him at DavidBenkof@gmail.com.