Friedman and Ravelo had previously been associates at another law firm and become close friends. Their alleged improper communications were discovered by Willkie after Ravelo and her husband were criminally charged in December with stealing from that firm, another law firm and MasterCard.
Roy Simon, a Hofstra University legal ethics professor, in a court filing supporting the objecting retailers, said Friedman crossed a line by passing important information to Ravelo, whose firm should in turn have been disqualified.
"In my three decades studying professional responsibility for lawyers," Simon wrote, "I cannot recall ever seeing such repeated and serious violations of professional duties by an attorney representing a class, or such willing participation in those violations by an attorney for a defendant in a class action."
The settlements were meant to resolve claims that the card networks overcharged merchants on interchange fees, or swipe fees, whenever shoppers paid with debit or credit cards.
In a Wednesday conference call discussing second-quarter results, MasterCard Chief Executive Ajay Banga called the lawyers' alleged conduct "pretty disappointing," but said he was "pretty confident" that the company's settlement will stand.
MasterCard spokesman Seth Eisen declined to elaborate. Visa spokeswoman Connie Kim declined to comment. American Express spokeswoman Marina Norville had no immediate comment.
Friedman, in a Wednesday filing in the American Express case, said none of the challenged communications "detracts from the conclusion that this settlement represents the best feasible settlement for the merchant class, and is fair and adequate by any measure."
The cases are In re: Payment Card Interchange Fee and Merchant Discount Antitrust Litigation, U.S. District Court, Eastern District of New York, No. 05-md-01720; and In re: American Express Anti-Steering Rules Litigation Antitrust Litigation in the same court, No. 11-md-02221.