NEW YORK – As reported by the Wall Street Journal earlier this week, the recent discovery of email communications between two opposing lawyers who are also close friends is threatening to scuttle a $6 billion class-action antitrust settlement between Visa Inc., MasterCard Inc. and millions of merchants.

The publication cites sources who say that lawyers representing the merchants, including Walmart Stores Inc., Home Depot Inc. and 7-Eleven Inc., will seek to unravel the three-year-old pact, as well as in a similar case involving a pending $79 million settlement involving American Express.

The email communications were discovered between attorney Keila Ravelo, who represented MasterCard in the antitrust case, and Gary Friedman, who—according to the Wall Street Journal, which reviewed hundreds of pages of court filings in the case—the merchants plan to contend that the communications between them involved confidential information and resulted in the merchants getting inadequate representation.

At a hearing last week, the magistrate who has been overseeing the sharing of the emails among the parties described the situation as “a serious breach,” according to a transcript of the hearing. Still, writes the Journal, “It isn’t clear if the exchange of documents between Ravelo and Friedman will be grounds for overturning the cases.”

Read more about the ongoing legal situation, here.