In 2003, the California Department of Justice developed a database—the Armed and Prohibited Persons System (APPS)—to automatically cross-reference the state’s firearm registry with the names of individuals legally prohibited from firearm ownership. Since then, it has been available to all California law enforcement agencies, whose officers are able to determine whether an individual is "armed and prohibited," by entering an individual's name.

In 2013, following the mass shooting at Sandy Hook Elementary School, California authorized $24 million (SB 140) to implement a large-scale effort to enforce existing restrictions on continued possession of firearms by prohibited persons. The Armed and Prohibited Persons System (APPS), an initiative of the California Department of Justice, uses that agency’s data to identify firearm owners among persons who have become subject to firearm prohibitions under California or federal law and then seeks to recover those firearms. After operating as a pilot program for several years, APPS has been implemented statewide under a statutory mandate.