The American Civil Liberties Union (ACLU) is suing the DC Metro for rejecting four ads for being “controversial,” claiming that it’s a violation of freedom of speech.

The organization has sued the WMATA on behalf of itself, abortion care provider Carafem, conservative commentator Milo Yiannopoulos and People for the Ethical Treatment of Animals (PETA).

According to the organization, DC Metro rejected ads featuring the First Amendment in English, Spanish and Arabic, an abortion medication, and an encouragement to “go vegan.” ACLU also said that ads for Yiannopoulos’ new book, “Dangerous,” were first accepted, then removed from the transit system after riders complained.

“To put it mildly, these plaintiffs have nothing in common politically. But together, they powerfully illustrate the indivisibility of the First Amendment,” the ACLU said in a blog post Wednesday. “Our free speech rights rise and fall together – whether left, right, pro-choice, anti-choice, vegan, carnivore, or none of the above.”

ACLU also took to Twitter to make the announcement. It said that the DC Metro’s ad policy violates the First Amendment by discriminating against ads or advertisers deemed controversial by agency officials, and that the four plaintiffs in the case span the political spectrum, illustrating the indivisibility of the First Amendment.

"In its zeal to not host offensive speech, the government has eliminated speech that makes us think, including the First Amendment itself," the organization tweeted.

Business Insider reached out to DC Metro for comment, which said that it changed its advertising forum to a nonpublic forum and adopted commercial advertising guidelines that prohibit issue-oriented ads, including political, religious and advocacy ads, since 2015.

"WMATA intends to vigorously defend its commercial advertising guidelines, which are reasonable and view-point neutral," a spokesperson told Business Insider.