Evan Schuman's StorefrontBacktalk

Retailers and the card brands have fights about card rules routinely. But it’s unusual for a senior executive at a card brand to publicly slap down a major chain. And it’s triply unusual when the chain is the world’s largest—Wal-Mart—and the slapper is the general counsel of MasterCard. The surprise topper: Wal-Mart officially conceded it was wrong.

This unusual tale comes to us courtesy of a Consumer Reports blog called Consumerist, which does an impressive job of tracking the retail space.

The Consumerist‘s story began with a Pennsylvania consumer’s complaint that he was instructed to show identification to make a $100 payment card purchase at the Willow Grove Wal-Mart. The cashier told him it was Wal-Mart policy to require a photo ID for all plastic purchases of more than $100.

“MasterCard communicated your negative experience to Walmart and their MasterCard Acquirer,” the attorney wrote to the consumer. “Walmart has assured us that asking for additional identification was not company policy and that they will correct this issue at store level through associate training and communication.”

The MasterCard rule, 5.8.4, is actually a little trickier. It says the merchant has the right to seek identification, but it can’t refuse to perform the transaction if the consumer refuses to comply.

This option puts associates in the awkward position of making a demand that they can’t sustain.

“I need to see some ID, please. You refuse? I was just kidding.” The result? Associates will stop asking for ID entirely, which is apparently what happened at the Willow Grove store the very next day, the complaining consumer reported.