Facebook is being sued for allegedly letting marketers exclude ads from being shown to specific “ethnic affinities,” genders, and religions.

A lawsuit seeking class action status filed in California federal court on Thursday alleges that Facebook’s ad targeting options violate federal fair housing and civil rights laws, which make it illegal to show a preference for certain groups of people in housing and employee recruitment advertisements.

The suit comes after a widely-read  ProPublica article in which the news organization created an ad targeting people who were interested in house-hunting. The news organization used Facebook’s advertising tools to prevent the ad from being shown to Facebook users identified as having African American, Hispanic, and Asian ethnic affinities.

According to the lawsuit, Facebook has enabled ads “with respect to the sale or rental of dwellings” as well as to employment “that indicate preference and discrimination based on race, color, religion, sex, familial status, and national origin.” The suit says such classes of people are protected by Title VII of the 1964 Civil Rights Act as well as the Fair Housing Act.

“No user can tell whether they are subject to illegal discrimination, bec ause the discrimination occurs with the ads they do not see,” says the lawsuit.Â

The lawsuit includes a chart outlining the various user characteristics that Facebook let’s advertisers hide ads from:

Public documents

“We’ve heard from groups and policy makers who are concerned about some of the ways our targeting tools could be used by advertisers,” Facebook told USA Today in response to ProPublica’s story and a letter from The Congressional Black Caucus condemning the tools. “We are listening and working to better understand these concerns.”

Facebook’s head of multicultural wrote a blog post last week explaining that, “If we learn of advertising on our platform that involves this kind of discrimination, we will take aggressive enforcement action.”

Facebook’s race-based ad targeting options have raised eyebrows before . Some observers noted that such ad targeting sometimes has legitimate uses .

The lawsuit says it is not seeking to completely get rid of the “exclude people” function in Facebook’s ad platform, which it says has some legal and desirable uses.Â

Facebook wasn’t immediately available to comment when contacted by Business Insider. The company has 21 days to respond to the lawsuit.