The suit says that this behavior violates the FHA, which has "prohibited both publishers and advertisers from targeting ads based on sex, family status, disability, national origin and other protected characteristics." The FHA was enacted fifty years ago, in an era of billboards, for rent signs and classified ads.

The claimants allege that Facebook has abused its enormous power in this new era of online advertising and should be held to the same standards. "Whereas in the past, the excluded group might see the "for rent" sign or newspaper classified ad because the ads were located in a public forum, the stealth nature of Facebook's technology hides housing ads from entire groups of people," wrote the claimants. "Facebook's algorithms can ensure exclusion and deny access to housing."

Update, 5:45PM ET: Facebook responded to the suit, saying "There is absolutely no place for discrimination on Facebook. We believe this lawsuit is without merit, and we will defend ourselves vigorously."