The United States District Court for Washington, D.C., Judge Richard Leon declared that the Federal Reserve was “non-compliant with Congress’s clear mandate” when it set fees for debit card transactions in 2011 right.

This is big news for retailers, who have to pay a fee, often referred to as a “swipe fee,” when a customer pays with plastic. Especially for small retailers, these swipe fees can quickly add up and take a bite out of paper-thin operating margins. For banks, these processing fees rake in serious revenue.

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