The ACLU is suing Metro for rejecting four “issues-oriented” advertisements, including one that promoted a new book by controversial alt-right writer Milo Yiannopoulos. (ACLU)

The American Civil Liberties Union is suing Metro, alleging the transit agency’s ad restrictions violate the First Amendment. The lawsuit also challenges Metro’s rejections of ads by Carafem, PETA, alt-right writer Milo Yiannopoulos and one the ACLU submitted.

The lawsuit, filed in U.S. District Court on Wednesday, centers on four ads: a PETA ad that encouraged riders to “Go Vegan,” an advertisement for an FDA-approved abortion pill, a promo for a book by Yiannopoulos, and an ACLU campaign that highlighted a quote from the First Amendment.

All were either rejected outright by Metro — based on its advertising guidelines that prohibit ads that are “issues-oriented” or “intended to influence members of the public regarding an issue on which there are varying opinions” — or were retroactively pulled from stations, trains and buses after riders complained.

“This case highlights the consequences of the government’s attempt to suppress all controversial speech on public transit property,” Arthur Spitzer, legal director of the ACLU-DC and lead counsel in the case, said in a statement. “The First Amendment protects the speech of everyone from discriminatory government censorship, whether you agree with the message or not.”

The ACLU said that Metro is enforcing its advertising guidelines capriciously, and that the prohibitions outlined in the guidelines are far too broad and wide-reaching.

The organization noted that any advertisement could potentially violate Metro’s policy, and that the transit agency has allowed other advertisements for organizations or issues that could be polarizing.

“By rejecting these ads and accepting ads from gambling casinos, military contractors, and internet sex apps, the [Washington Metropolitan Area Transit Authority] showed just how subjective its ban is,” the  statement said.

“WMATA’s policy is an attempt to silence anyone who tries to make you think. Any one of these advertisements, had it passed the WMATA’s censor, would have been the subject of someone’s outraged call to the WMATA,” the ACLU added. “The First Amendment doesn’t, and shouldn’t, tolerate that kind of impoverishment of our public conversation. Not even in the subway.”

Carafem, the company whose advertisements for abortion pills were rejected by Metro, said it is a health-care provider, not an advocacy group, meaning its ads do not violate Metro’s policy.

“The abortion pill is, of course, both FDA-approved and accepted by the American Medical Association. We are a healthcare provider, not an advocacy group. Metro’s ban of our ads claimed that they were ‘issue-oriented’ and ‘provided a medical statement which can only be accepted from a government health association,’ ”  Melissa Grant, Carafem’s chief operations officer, said in a statement. “This is obviously inaccurate — we’re publicizing our services like any other health care provider.”

Metro did not immediately respond to a request for comment.