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Report · September 2019

Key Factors in Arrest Trends and Differences in California’s Counties

Magnus Lofstrom, Brandon Martin, Justin Goss, Joseph Hayes, and Steven Raphael

This research was supported with funding from the Arnold Ventures.

Police officers in California make more than a million arrests per year. While officers make arrests to enforce laws and protect public safety, arrests can have wide-ranging consequences-including the risk of injury for both officers and suspects. Despite the effects on individuals and the broader community, little is known about the factors underlying arrest trends. Concerns about racial disparities-and ongoing debates about policing and community relations-further highlight the need for a better understanding of law enforcement and the use of public resources in making arrests.

In this report, we examine factors in statewide arrest trends as well as differences in arrest rates and racial disparities across counties in California. We analyze the role of crime rates, recent criminal justice reforms, and county-level factors such as demographics, law enforcement staffing, jail capacity, and economic conditions. We find:

  • Significant decreases in arrests statewide reflect improvements in public safety. Declining arrest rates have generally mirrored decreasing crime rates in the last few decades. However, in recent years, arrest rates have continued to drop, despite a slight uptick in some violent crimes.
  • Arrest rates dropped substantially in the wake of public safety realignment and Proposition 47. Driven by declines in misdemeanor traffic and alcohol-related arrests, the overall arrest rate decreased about 7 percent after the implementation of realignment in 2011. The arrest rate went down by another 11 percent after Proposition 47 in 2014, driven by declines in felony arrests, especially for drug offenses.
  • Local crime rates largely account for differences in arrests across counties. Arrest rates vary dramatically across counties, and about three-fourths of this variation can be explained by county differences in crime rates.
  • Counties with the highest arrest rates tend to have poorer economic conditions-as measured by unemployment, poverty, and average earnings. These counties have arrest rates that are two to three times higher than counties with the lowest arrest rates. High-arrest counties also tend to have lower shares of nonwhite residents, higher shares of young adults, lower population density, lower levels of educational attainment, and greater jail capacity. Notably, a greater number of law enforcement officers is not associated with a significantly higher arrest rate.
  • Counties with the highest levels of racial disparity tend to be relatively affluent. In these counties, the African American arrest rate is about six times higher than the white arrest rate, compared to almost double among counties with relatively low racial disparity. Counties with high racial disparity generally have lower shares of African American residents, higher levels of educational attainment, and greater jail capacity. While arrest rates are higher in relatively poor counties with lower shares of nonwhite residents, racial disparities in arrests tend to be lower in these counties.

It is important to note that these results should not be interpreted as causal. For example, although African Americans are arrested at a higher rate in more affluent counties, this does not necessarily imply that greater affluence would lead to an increase in racial disparity. Nevertheless, these associations do suggest that if policymakers wish to lower arrest rates-motivated by factors such as lowered use of public resources and costs, as well as risk for officers and suspects-improvements in local factors like public safety (which may be affected by policing), economic conditions, and educational attainment could lead to fewer arrests and the need for a smaller county correctional system. And while concerns about policing and community relations tend to focus on poorer urban areas, our findings suggest that efforts in wealthier areas are also needed to meaningfully reduce racial disparities.

While police officers’ decisions no doubt have important implications for how laws are enforced, other aspects of the local environment may also play an important role in arrests and racial disparities. Understanding this broader context will be important as the state and localities continue to monitor police interactions with the public and strive to improve equity in law enforcement while maintaining public safety.


Criminal Justice Population