Facebook flat-out 'lies' about how many people can see its ads – lawsuit

"Based on a combination of publicly available research and Plaintiffs' own analysis, among 18-34 years-olds in Chicago, for example, Facebook asserted its Potential Reach was approximately 4 times (400 per cent) higher than the number of real 18-34 year-olds with Facebook accounts in Chicago," the complaint states.

What's more, the court filing contends that former Facebook employees, described as confidential witnesses, have acknowledged that Facebook is fine with inflated numbers.

A second former Facebook employee is said to have observed that "Facebook does not care about the accuracy of information related to the number of users so long as advertising revenue is not negatively affected."