24 GOP attorneys general warn Visa, AmEx, and Mastercard about using a code that identifies purchases at gun stores

• AGs from 24 states sent a letter threatening to take action over a new merchant code for gun stores.
• The move follows the International Organization for Standardization's recent vote to create the code.
• All three credit-card companies recently said they have adopted the standard.

The Republican attorneys general of 24 states are threatening to "marshal the full scope of our lawful authority" as Visa, American Express and Mastercard adopt a new merchant category code recently created for gun and ammunition stores.  

The AGs sent a letter Tuesday to the CEOs of American Express, Mastercard, and Visa. The letter was led by the attorneys general of Tennessee and Montana. The Wall Street Journal was first to report the story.

All three payment processors have adopted the code, NPR reported. 

The attorneys general warned that tracking the data could lead to misuse, whether intentional or unintentional. "Creating and tracking this data only matters if your institutions are considering using that information to take further, harmful action—like infringing upon consumer privacy, inhibiting constitutionally protected purchases by selectively restricting the use of your payment systems, or otherwise withholding your financial services from targeted "disfavored" merchants."

They said using a merchant code for gun stores would be an inaccurate method for keeping track of firearms purchases. "This categorization would not recognize the difference, for example, between the purchase of a gun safe and a firearm. Nor would it capture firearm purchases made at department stores, resulting in arbitrarily disparate treatment of "gun store" merchants and consumers."

The coordinated move came after the Geneva-based nonprofit International Organization for Standardization (ISO) approved the creation of the merchant code earlier this month. A spokesperson for the National Rifle Association told Insider the vote was "nothing more than a capitulation to anti-gun politicians and activists bent on eroding the rights of law-abiding Americans one transaction at a time."

Gun rights advocates, including the NRA, have expressed concerns that the new merchant category code would effectively create a gun registry, and put gun owners at risk. 

This would "create the obvious risk that law-abiding consumers' information will be leaked, discovered, hacked, or otherwise obtained and misused by those who oppose Americans exercising their Second Amendment rights," per the letter. 

Visa referred Insider to a statement it issued on Sept. 13, a few days after the ISO decision: "Many misunderstand what that means and are, in turn, advocating the use of MCCs to "track" gun sales as a potential tool in combatting gun violence," Visa wrote.  "That's not what merchant codes are designed for, nor should they be. MCCs already exist for hundreds of different businesses, including beauty salons, bookstores, newsstands, bowling alleys and bakeries, among many others."

The company said that when Visa and other payment networks process a transaction, they don't have visibility over the items consumers buy.

In a separate statement to Insider, Mastercard said it "respects individuals' right to transact privately with others" and that the creation of the merchant code would not cause the company to deviate from its principles, "Quite simply, we allow lawful purchases on the network. This ensures the application of a clear, consistent, and reliable standard upon which consumers, businesses, and governments across the world can understand and rely."

American Express did not immediately respond to Insider's request for comment.

The letter was signed by attorneys general from these 24 states: Alabama, Alaska, Arizona, Arkansas, Florida, Georgia, Indiana, Kansas, Kentucky, Louisiana, Mississippi, Missouri, Montana, Nebraska, New Hampshire, Ohio, Oklahoma, South Carolina, Tennessee, Texas, Utah, Virginia, West Virginia, Wyoming.