When we learned earlier this year that Facebook allows advertisers to target users based on their race, it appeared to simply be just another attempt by the social media giant to allow for ads targeted with the most granular of parameters. However, a new report from ProPublica reveals another — possibly illegal — side to that story. In addition to, say, allowing a company to request that their ad be shown to a specific group of people, Facebook permits advertisers to select what "ethnic affinity" they would like to exclude. Some of those options include "African American," "Asian American," and "Hispanic."

“This is horrifying," civil rights lawyer John Relman told ProPublica. "This is massively illegal. This is about as blatant a violation of the federal Fair Housing Act as one can find.”

The Fair Housing Act of 1968 states that it is illegal to "make, print, or publish, or cause to be made, printed, or published any notice, statement, or advertisement, with respect to the sale or rental of a dwelling that indicates any preference, limitation, or discrimination based on race, color, religion, sex, handicap, familial status, or national origin.”

A theoretical ad for housing on Facebook that excluded any of the above groups might run afoul of the law.

Facebook, for its part, denies that it's doing anything wrong and says that it doesn't even know the race of its users. The company doesn't directly ask users that information, and Facebook's privacy and public policy manager, Steve Satterfield, claimed that “Ethnic Affinity,” as Facebook calls it, is something other than a user's race — although that it is included in the “Demographics” category of the ad tool seems to suggest otherwise. And anyway, Satterfield told ProPublica, the company would pull any ads that were in violation of the law.

“We take a strong stand against advertisers misusing our platform: Our policies prohibit using our targeting options to discriminate, and they require compliance with the law,” he said. “We take prompt enforcement action when we determine that ads violate our policies."

However, as a test, ProPublica purchased a housing ad that excluded various minority groups. It was approved by Facebook within 15 minutes. When asked about that ad, a Facebook spokesperson reportedly declined to comment.

Previously: Facebook Knows Your Race, Sends You Targeted Ads