The Fed said:
A payment card network inhibits a merchant's ability to route electronic debit card transactions if it, by network rules, standards, specifications, contractual agreements, or otherwise, requires the merchant to allow the cardholder to make the choice of EMV chip application on a debit card, where one application routes only to a single network. Such a requirement is not compliant with section 235.7 of Regulation II because it prevents the merchant from directing the routing of electronic debit transactions.
By limiting consumers' choice of routing at the point of sale, this interpretation of the Durbin Amendment could push more debit transactions to be processed as PIN transactions rather than via signatures.
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