The decision comes as the banking industry makes a furious effort in Springfield to convince lawmakers to repeal the Illinois Interchange Fee Prohibition Act, which exempts state and local taxes and tips from credit card processing fees, ahead of its July 1 implementation. The retail industry said the law will save merchants and restaurants money, while the bankers claim it will upend the payment ecosystem across the state and disadvantage financial institutions who are footing the bill to upgrade their systems to accommodate it.

In February, a judge denied the banking lobby’s attempts to stop the law from taking effect. Judge Virginia Kendall of the U.S. District Court for the Northern District of Illinois acknowledged the banking industry’s claims that it would be onerous to adapt payment systems to meet the new requirements, but she said the law does not interfere with them operating in a way that federal law permits.

But the U.S. Office of the Comptroller of the Currency proposed a rule in April protecting federally chartered banks from the state law, which is the first of its kind. After releasing the language of the rule, the OCC filed a friend of the court brief with the appellate court backing the banks.