Daniel Fisher at Forbes explains:
…The rise of the “confidential witness” can be traced to the Public Securities Litigation Reform Act and subsequent Supreme Court rulings, under which class-action lawyers are required to do more than just point out the obvious, that a stock price fell. They need to state “particularized facts” giving a strong inference that somebody in management, not just a faceless corporate entity, did something he or she knew was fraudulent.
To get over this hurdle, class-action lawyers frequently call upon nameless “confidential witnesses” who apparently are willing to speak with plaintiff lawyers but live in fear of their identities being revealed to anyone else.
Funny thing is, the testimony of these confidential witnesses on eventually reaching the light of day keeps not backing up the propositions the lawyers said it did. The newest embarrassment afflicts Robbins Geller, a successor law firm to Bill Lerach’s Coughlin Stoia. More: ABA Journal; City of Livonia Employees Retirement System v. Boeing.