SACRAMENTO, Calif. (AP) — Beginning Monday, a California law will require credit card networks like Visa and Mastercard to provide banks with special retail codes that can be assigned to gun stores in order to track their sales.

But new laws will do the exact opposite in Georgia, Iowa, Tennessee and Wyoming by banning the use of specific gun shop codes.

The conflicting laws highlight what has quietly emerged as one of the nation’s newest gun policy debates, dividing state capitols along familiar partisan lines.

Some Democratic lawmakers and gun-control activists hope the new retail tracking code will help financial institutions flag suspicious gun-related purchases for law enforcement agencies, potentially averting mass shootings and other crimes. Lawmakers in Colorado and New York have followed California’s lead.

“The merchant category code is the first step in the banking system saying, `Enough! We’re putting our foot down,'” said Hudson Munoz, executive director of the nonprofit advocacy group Guns Down America. “`You cannot use our system to facilitate gun crimes.'”

But many Republican lawmakers and gun-rights advocates say the retail code could lead to unwarranted suspicion of gun buyers who have done nothing wrong. Over the past 16 months, 17 states with GOP-led legislatures have passed measures prohibiting a firearms store code or limiting its use.

“We view this as a first step by gun-control supporters to restrict the lawful commerce in firearms,” said Lawrence Keane, senior vice president of the National Shooting Sports Foundation, an industry group that backs laws blocking use of the tracking code.

The surge of legislation targeting firearm store category codes addresses a behind-the-scenes aspect of electronic financial transactions. The International Organization for Standardization, based in Geneva, sets thousands of voluntary standards for various fields, including category codes for all kinds of businesses, from bakeries to boat dealers to bookstores.

Those category lists are distributed by credit card networks to banks, which assign particular codes to businesses whose accounts they handle. Some credit card issuers use the category codes for customer reward points.

The codes can bexused by financial institutions to help identify fraud, money laundering or unusual purchasing patterns that are reported as suspicious activities to the U.S. Treasury Department’s Financial Crimes Enforcement Network.

Banks and other depository institutions filed more than 1.8 million confidential reports in 2022 flagging more than 5.1 million suspicious activities. About 4% of annual reports lead to follow-up by law enforcement and an even smaller percentage to prosecution, according to the Bank Policy Institute, a trade group representing large banks.

Stores that sell guns have previously been grouped with other retailers in merchant category codes. Some have been classified as sporting goods stores, others as miscellaneous and specialty retail shops.