Illinois enacted a law that prohibits a credit card holder’s bank from charging or receiving interchange fees on the portions of transactions that include Illinois state or local taxes and gratuities, in effect starting July 1, 2025. IL Interchange Fee Prohibition Act (“IFPA”) 815 ILCS 151/150-1 et seq. The Illinois Bankers Association and others collectively sought relief in the federal courts to prevent the IFPA from taking effect and asserted that the IFPA is preempted by federal laws, is unconstitutional under the Supremacy Clause of the United States Constitution, and is discriminatory under the dormant Commerce Clause of the United States Constitution because it imposes a regulatory measure that “benefit[s] in-state economic interests by burdening out-of-state competitors.” Compl. ¶ 202 to 224. They won a preliminary injunction that temporarily blocks the law while the challenge proceeds. Illinois Bankers Association’s et al. v. Kwame Raoul, in his official capacity as Illinois Attorney General, No. 24 C 7307 (N. D. Ill. Dec. 20, 2024). 

A preliminary injunction in any court requires, at a minimum, the court to believe that the party seeking the injunction has a reasonable likelihood of success on the merits of the actual case and will suffer irreparable harm if application of the law is not stayed while the case proceeds. This means at least two things. First, you have to be prepared for a mini-proceeding on the case before you get to the trial stage at which you would put on your full case. That is, if you cannot demonstrate that you are likely to ultimately win and you would be harmed by not halting the law early, why would the court want to stay the application of a law at an early stage of your case? Second, if you win a preliminary injunction, you are more likely to ultimately prevail.

The court found that:

1. the IFPA prohibits charging or receiving interchange fees on the portion of a credit card transaction that includes Illinois state or local taxes or gratuities; 
2. the IFPA defines an interchange fee as “a fee established, charged, or received by a payment card network for the purpose of compensating the issuer for its involvement in an electronic payment transaction[;]” 
3. under the federal National Bank Act powers, banks are authorized to engage in any activity that is “incidental to the business of banking [;]” 
4. Office of the Comptroller of the Currency guidance makes clear that processing credit and debit card transactions is part of the business of banking; 
5. the IFPA directly regulates credit and debit card transactions by dictating the amount that banks can charge for a transaction; and 
6. by barring a credit card issuer from charging interchange fees on state and local taxes and gratuities, the IFPA alters a bank’s right to determine how best to structure their non-interest fee arrangements with merchants.

The banks demonstrated irreparable harm by proving that costs to make changes to their payment processing systems (the current systems do not distinguish whether the transaction is for state and local tax or gratuities) would not be recouped if the law was later struck down.

The takeaway here is that a preliminary injunction and a challenge in federal court are powerful tools that can add leverage if the case is right for using them. Often state tax challenges are prohibited in federal courts under the Tax Injunction Act, which provides that federal courts “shall not enjoin, suspend or restrain the assessment, levy or collection of any tax under State law where a plain, speedy and efficient remedy may be had in the courts of such State.” 28 USC § 1341. However, if you can get there, make a federal case out of it!