The American Civil Liberties Union is filing charges against Facebook for allegedly running discriminatory job ads that appeared only to men, something that is illegal under the Civil Rights Act. The ACLU says that Facebook’s platform allowed 10 employers, including a software developer and a police department, to run ads that excluded women and non-binary users, and it says the social network should be held liable for creating the tools to offer these allegedly discriminatory ads.

The complaint is being filed with the United States Equal Employment Opportunity Commission, a federal agency that oversees charges of workplace discrimination. It’s filed on behalf of three women who say they were discriminated against, but the complaint also hopes to cover “millions” of women who were excluded from seeing job ads by Facebook and various employers.

Facebook has been scrutinized over targeted housing ads, too

Facebook’s platform has become immensely valuable because of its ad-targeting capabilities and wealth of personal data on users. But those same capabilities can allow for problematic and discriminatory targeting if used unchecked. The ACLU says that’s what happened here when Facebook did not prevent employers from running ads that included gender-based targeting. The complaint alleges some employers used illegal age-based targeting as well.

In an emailed statement, Facebook spokesperson Joe Osborne said that discrimination is “strictly prohibited in our policies” and that “over the past year, we’ve strengthened our systems to further protect against misuse,” mirroring language Facebook has used in the past. Osborne added, “We are reviewing the complaint and look forward to defending our practices.”

This is not the first time Facebook has run into this kind of criticism. The company came under extensive scrutiny for allowing housing ads to exclude people based on race and other protected factors, and it eventually came to an agreement to end those advertisements nationwide. It later removed 5,000 categories that allowed advertisers to exclude religious and ethnic minority groups after the Department of Housing and Urban Development filed a complaint.

As the ACLU points out in a press release, online platforms are generally not liable for user-posted content, which would include ads. But the group argues that Facebook should be held accountable in this case because it created and ran the ad-targeting system and then delivered the ads based on categories with the potential for discrimination.