Illinois senator Richard Durbin, a Democrat, has defended the debit card interchange amendment that bears his name, suggesting that the bank that has brought suit against it in federal court does not really understand it.

TCF National Bank, headquartered in Minnesota, has filed suit in federal court alleging that the debit card interchange regulating amendment is unconstitutional. Durbin took on that claim directly.

"TCF's complaint not only fundamentally misunderstands the law regarding interchange fees, but it also ignores the facts," Durbin said. "The law in no way addresses the fees TCF, or any other bank, can charge and it does not set interchange rates. Our language simply ensures that debit interchange fees charged to retailers by the card networks–not the banks–are 'reasonable and proportional' to the cost of processing transactions and provides competition in an area of the market where there's none.