Missouri Attorney General Eric Schmitt announced today that his office joined a coalition of 24 attorneys general in sending a letter to Stephen J. Squeri (CEO of American Express, Inc.), Michael Miebach (CEO of Mastercard, Inc.), and Alfred F. Kelly Jr. (CEO of Visa, Inc.) vehemently opposing their decision to enact the International Organization for Standardization’s (ISO) Merchant Category Code, which involves applying a separate code identifying sales at U.S. gun stores.