The year 2010 will be remembered as when the federal government got involved in how much interchange banks and credit unions earn on their debit card transactions.

The regulations came in form of an amendment to the Dodd-Frank Wall Street Reform and Consumer Protection Act that had been principally sponsored by Sen. Richard Durbin (D-Ill.).

The amendment was the unexpected culmination of years of lobbying from merchant associations that complained they were having to pay too high a price for accepting credit and debit cards. But all the lobbying came to naught until, according to one source, Durbin was contacted by a very important constituent.