The New York Times’ Christmas Eve feature about mass shooters buying guns with credit cards has already been ably dismantled by Kevin Williamson, David French, and just about everyone I follow on Twitter, but I wanted to add a quick point. Specifically, these few paragraphs from the Times story are important but seldom noted by the piece’s critics (emphases mine):

A labyrinth of rules prevents banks and credit-card networks — many of which also handle debit card transactions — from seeing exactly what customers are buying. Retailers have historically resisted providing item-by-item information . . . for fear that banks would sell that information or use it to steer customers to rival merchants.

In the case of gun purchases, even the nature of the retailer can be obscure: The Merchant Category Code, which identifies the type of store that sold an item, is the same for gun shops and sporting goods stores.

But retailers have the ability to send far more detailed transaction information.

A feature known as a “boxcar” allows retailers to tag transactions with extra data. It is often used by online retailers to send the bank details about consumer behavior, such as the device used to make a purchase and the location of the buyer.

If banks required retailers to transmit details on sales of guns and ammunition, they would be able to make more informed decisions about transactions.

Walmart and Dick’s Sporting Goods this year announced that they would not sell firearms to anyone under 21. If banks chose to use the systems they already have in place, they might decide to monitor such customers, perhaps preventing them from buying multiple guns in a short period of time.

. . .

Banks could also add information about gun sales to the infrastructure they already use to help the government investigate other criminal activity.