ImportanceA total of 19 states and the District of Columbia now have extreme risk protection order (ERPO) or similar policies, and others are considering them; however, little research exists describing their use.ObjectiveTo characterize early use of California's ERPO policy by providing the first aggregate, statewide description of ERPOs, individuals subject to them, and petitioners.Design, setting, and participantsThis cross-sectional study analyzed 1076 respondents to ERPOs recorded in the California Department of Justice California Restraining and Protective Order System from 2016 to 2019. Descriptive analyses of orders issued between January 1, 2016, and December 31, 2019 in California were performed, and univariate Moran I was calculated to examine county-level spatial autocorrelation of the policy's use.Main outcomes and measuresThe primary study outcomes included the characteristics of ERPO respondents (demographic characteristics), petitioners (law enforcement vs family or household members), and orders (type and service) as well as temporal and spatial variation in policy use during the first 4 years of implementation.ResultsOf 1076 respondents during the study period, most were men (985 [91.5%]) and white individuals (637 [59.2%]), with a mean age of 41.8 years (range, 14 to 98 years). A law enforcement officer was the petitioner in 1038 cases (96.5%). The number of respondents increased during the study period from 70 in 2016 to 700 in 2019, and there was substantial county-level variation in ERPO use (ranging from 0 to 354 respondents), with significant spatial clustering in counts of ERPO respondents among neighboring counties (observed Moran I, 0.18, mean [SD] Moran I from reference distribution, -0.01 (0.05); z value, 3.58; Pβ=β.004).Conclusions and relevanceThis study, among the first to describe the early utilization of an ERPO or similar policy, found a substantial increase in the use of ERPOs in California from 2016 to 2019. These results could inform policy makers and other stakeholders involved in policy implementation and outreach in California and elsewhere. Similar studies in other states would be useful to understand variation