But the law makes an exception when a debtor accidentally wires money to a creditor Okay, but Citibank wasn't the debtor here, they were simply the middleman.

But the law makes an exception when a debtor accidentally wires money to a creditor Okay, but Citibank wasn't the debtor here, they were simply the middleman. And: "To believe that Citibank, one of the most sophisticated financial institutions in the world, had made a mistake... would have been borderline irrational" Sure, if you hear hoofbeats, the likely guess is horses, not zebras. But if someone calls you up and says "Hey, I got some nice pics of zebras running by your house" then you know the probable guess was wrong, and should act accordingly. Absolutely the mistake was Citibank's fault. Maybe you think that means, inherently, that they should lose the case. But if you look at the actual laws on the books, I really don't understand how the interpretation of the laws comes down against Citi here. Though a half $billion mistake on UI design might still be a very beneficial lesson for the entire UX design community to remember.