The Durbin Amendment, passed as part of the Dodd-Frank financial reform legislation in 2010, required the Federal Reserve to limit fees charged to retailers for debit card processing.
Interchange fees are paid to banks by merchants for the privilege of accepting payment cards. Merchants and card-issuing banks have long fought over these fees. Prior to the Durbin Amendment, card swipe fees were previously unregulated and averaged about 44 cents per transaction.
However, this does not mean the savings was passed onto you. Instead it increased the profits for the processing banks and agents. This happened because it lowered the processors buy-rate cost while still keep the markup to the merchants at the same cost.