And that means stores with a lot of small-ticket sales, such as coffee shops and gas stations, may force or coax consumers into paying with plain old cash for purchases under a certain amount, experts predict.

While it makes sense for some businesses to operate on a cash-only basis, for others it could be “financial suicide,” said Ann Latham, president of Uncommon Clarity, Inc., a Massachusetts-based consulting firm.

Kamal Grant, owner of Sublime Doughnuts near Georgia Tech, said he fears any move to restrict plastic will drive away customers. When he did not accept American Express cards because of their high fees, Grant said, some people walked out without buying the doughnuts they had ordered.

The interchange fee cap also will “heighten the segmentation of consumers who can increase spending using credit cards,” [James L.] Brown said.

Another part of the Durbin amendment restricted banks from signing or maintaining exclusive debit-processing deals with networks. Now issuers must have agreements with at least two networks to process debit transactions on every card — a relatively complicated arrangement that is causing banks some headaches.

The law was supposed to help small retailers by providing them relief from debit card interchange fees, but the unintended consequence has been higher prices as consumers shift towards credit instead of debit.

“But consumers have not been spared anything as the Durbin Amendment has shifted $12 billion hand-over-fist to some of the nation’s wealthiest retailers, such as Walmart, Home Depot and Walgreens — firms that all lobbied for the price controls to fatten their own pocketbooks.”

“What’s still missing from the retailer argument is any clear evidence that cost savings are being passed along to consumers, as merchant lobbyists promised. Maybe that will come later. But in the meantime, Congress and the Fed should steer clear of any more price fixing.”

“Retailers have kept at least $825 million to themselves since the Durbin Amendment was enacted in October.”

“[Consumers] have not enjoyed any pass-through benefit from lower swipe fees in the price of retailer goods and services…”