CUNA and NAFCU were among a coalition of financial institutions which filed a friend of the court brief on Thursday against a case brought by merchants seeking to force the Federal Reserve to further cut debit interchange.

The merchants brought the case after the Federal Reserve's regulation implementing the Durbin amendment to the Dodd-Frank Act did not cut debit interchange as deeply as they believed it should.

In the brief, which included the American Bankers Association and other banking groups, the coalition took pains to point out they were not fans of the existing regulation.

“Amici are not here to defend the Final Rule,” the coalition wrote. “The merchants bring their lawsuit in pursuit of even deeper cuts in issuers' interchange-fee revenues, seeking to reap the benefits of debit card transactions and innovation in the electronic-payments system practically for free – an unwarranted, unfair and unprecedented windfall.”