Here. For example, advertisers can specify that their housing ads not be shown to African-Americans, Asian-Americans, Hispanics, etc., in apparent violation of various laws. HUD is now reported to be looking into the matter, and a class action suit has been filed. It is not clear from the story whether the option is limited to housing ads or extends to other types or ads, such as for loans, or whether advertisers can also ask that their ads not be shown to people based on other demographic criteria, such as age or gender. Nor is it clear how effective Facebook is at screening out people with the specified characteristics.