A proposed class action lawsuit alleging Facebook's ad placement tools facilitate discrimination against older job seekers has been expanded to identify additional companies, further widening the latest front in claims that candidates are being filtered out by gender, geography, race, and age.

“When Facebook's own algorithm disproportionately directs ads to younger workers at the exclusion of older workers, Facebook and the advertisers who are using Facebook as an agent to send their advertisements are engaging in disparate treatment,” a communications union alleged in the amended complaint—citing a legal test for employment discrimination—filed Tuesday in San Francisco federal court. The union added claims under California's fair employment and unfair competition statutes to the lawsuit, which was initially filed in December.

The Communications Workers of America (CWA) is suing on behalf of union members and other job seekers who allegedly missed out on employment opportunities because companies used Facebook's ad tools to target people of other ages. The original filing named defendants are Amazon.com Inc., Cox Media Group, Cox Communications Inc., and T-Mobile, as well as what the union estimates to be hundreds of employers and employment agencies who used Facebook's tools to filter out older job hunters when seeking to fill positions.