The fight against mass shootings just got a win ... from credit card companies

The effort to reduce mass shootings got a win over the weekend, as American Express, Mastercard, and Visa all said they would adopt a new code to categorize sales at gun shops. That in turn could help flag suspicious purchases that could be the prelude to a mass shooting—for instance, the shooter responsible for the Pulse Nightclub massacre in 2016 spent $26,000 on guns and ammunition just a week earlier.

The move by the credit card processing companies followed the announcement of the new code by the International Organization for Standardization (ISO), which Sen. Elizabeth Warren called “an important step towards improving coordination with law enforcement and preventing gun violence.”