Milo Yiannopoulos got some unexpected support this week from the American Civil Liberties Union.

The former Breitbart news editor released a self-published memoir and by now Best-Seller, “Dangerous”, last month. In a lawsuit filed Wednesday, the ACLU argued that the Washington Metropolitan Area Transit Authority violated Yiannopoulos’ right to free speech when it refused to let him promote the book on the Washington, D.C., metro.

The British-born Yiannopoulos is among several clients ― including abortion and birth control provider Carafem and the animal advocacy group People for the Ethical Treatment of Animals ― named in the ACLU’s lawsuit, according to the Los Angeles Times. The suit stems from WMATA guidelines that forbid advertisements “intended to influence members of the public regarding an issue on which there are varying opinions,” which the ACLU believes is too vague. Given Yiannopoulos’ history of criticizing Muslims, feminists, the LGBTQ community and the Black Lives Matter movement, however, the conservative author’s inclusion in the suit sparked instant controversy.

Acknowledging that 32-year-old Yiannopoulos “trades on outrage,” ACLU officials nonetheless explained their choice to defend him in a Wednesday blog post on the group’s official website. “The ACLU condemns many of the values he espouses (and he, of course, condemns many of the values the ACLU espouses),” they wrote.

Though WMATA initially accepted the “Dangerous” ads and “displayed them in Metro stations and subway cars,” they were removed 10 days later after passengers complained, the ACLU alleges. “To anyone who’d be outraged to see Mr. Yiannopoulos’ advertisement — please recognize that if he comes down, so do we all,” ACLU officials wrote. “The First Amendment doesn’t, and shouldn’t, tolerate that kind of impoverishment of our public conversation. Not even in the subway.”

James Esseks, who is the director of the ACLU’s LGBT & HIV Project, defended his organization’s decision to represent Yiannopoulos in a second blog, also published Wednesday. “Some people may say that Mr. Yiannopoulos’ offensive speech sets him apart and doesn’t deserve to be defended. But the sad reality is that many people think that speech about sexuality, gender identity, or abortion is over the line as well,” he wrote. “If First Amendment protections are eroded at any level, it’s not hard to imagine the government successfully pushing one or more of those arguments in court.”

Still, support for the ACLU’s defense of Yiannopoulos was not unanimous across the organization. Chase Strangio, an ACLU staff attorney best known for defending U.S. military whistleblower and transgender activist Chelsea Manning, blasted the decision in a lengthy note posted to Twitter on Wednesday, presenting, however, a questionable argument.

Calling Yiannopoulos “vile” and “a reprehensible person,” Strangio wrote, “I don’t believe in protecting principle for the sake of principle in all cases. His actions have consequences for people that I care about and for me.”

Meanwhile, Yiannopoulos told the Los Angeles Times that he was “glad that the ACLU has decided to tackle a real civil rights issue,” adding, “Free speech isn’t about only support[ing] speech you agree with, it is about supporting all speech — especially the words of your enemies. Strong opponents keep us honest.”