Seven years ago, Berger & Montague launched an unusually complex antitrust case that was anything but a slam-dunk. This year, the investment paid off in a big way. The firm helped obtain a $7.25 billion preliminary settlement — the largest monetary antitrust settlement on record — as co-lead counsel on an antitrust class action against credit card giants Visa Inc. and MasterCard Inc. in July. It also triggered major reform of the transaction rules that govern the banks and merchants.

“We felt that this was a case where there was a definite need — the merchants had been complaining about this system for a long, long time, and this was a good opportunity to do it,” said Berger & Montague president H. Laddie Montague Jr., who led the case with partners Merrill Davidoff, Bart Cohen and Michael Kane.

With co-counsel from Robins, Kaplan, Miller & Ciresi and Robbins Geller Rudman & Dowd, the firm represented 7 million American merchants who accept credit and debit card payments.

Discovery included hundreds of depositions; production and review of tens of millions of document pages; and reports from more than a dozen experts. The team had to prove the credit card companies conspired to fix the fee merchants pay on every transaction. The team expects final approval of the settlement during 2013.

Philadelphia-based Berger & Montague has long enjoyed a reputation as an aggressive firm that wins big cases. “I think our work and success in this case expands our reputation in the field and increases the reach of our firm, the ability of our firm to attain leadership positions in cases going forward,” managing partner Eric Cramer said.

Berger & Montague played a lead role throughout the year in major cases. Cramer and partner David Sorensen are co-lead counsel in pending class actions against the pharmaceutical giants that produce Lipitor and Effexor.

Another pharmaceutical case the firm is handling with co-counsel from Garwin Gerstein & Fisher might be headed to the U.S. Supreme Court, Cramer said. The plaintiffs won a key ruling in the U.S. Court of Appeals for the Third Circuit that revived an antitrust case against Schering-Plough (now Merck & Co. Inc.) and Upsher-Smith Laboratories Inc. over allegations they paid generic drug makers to delay entry of products to the market.

Davidoff negotiated a $49.5 million settlement with American Express Co. in April over fixed foreign transaction fees. The deal followed appellate reversal of a district court ruling that would have allowed AmEx to invoke arbitration clauses.