This bill seeks to prevent states from prohibiting or otherwise deterring the use of merchant category codes (MCCs) established by the International Organization for Standardization. It specifically targets MCCs used to identify firearm merchants , ammunition merchants , and payment card transactions involving the purchase of firearms, ammunition, or related accessories. The legislation amends federal law to establish this preemption, ensuring that states cannot interfere with the application of these financial transaction codes. The Attorney General is granted the authority to enforce these provisions by bringing civil actions in appropriate district courts.