Firearm purchases without background checks in California

Background checks are designed to prevent firearm acquisition by people prohibited from purchasing or possessing firearms. There is limited information about background checks, particularly on a state by state basis. We conducted a state-representative, probability-based, Internet survey of California adults in 2018 (n=2558; completion rate 49%) to describe where, when, and how firearms are acquired and to estimate the proportion of current firearm owners who purchased their most recent firearm without a background check. An estimated 17.2% (95% CI: 9.6-28.8) of firearm owners who purchased their most recent firearm within California in 1991 or later, following implementation of the state's comprehensive background check law, reported doing so without a background check. This percentage was 44.6% (95% CI: 27.1-63.5) among owners who purchased their most recent firearm before 1991 and 27.1% (95% CI: 13.1-47.7) among those who purchased their most recent firearm outside California. Firearm purchases without background checks occurred more often for firearms purchased from private sellers (72.3%; 95% CI: 35.5-92.5) than retailers (8.5%; 95% CI: 3.4-19.7). Overall, firearm purchases without background checks are considerably less common in California than in states without regulations on private sales. However, gaps in implementation and proper enforcement remain. Future research could investigate reasons for such lapses, as well as complementary state policy approaches that require background checks prior to point of purchase.