A federal judge on Wednesday struck down federal regulations on debit-card transaction fees, finding that the Federal Reserve adopted rules that "inappropriately" inflated fees by billions of dollars.

The decision was a win for retailers and retail trade associations that challenged the debit-transaction regulations adopted by the Fed in 2011. The agency, the retailers claimed, ignored Congress' directives to consider only certain costs in setting the fee standard and, as a result, set it too high.