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Blog Post · May 11, 2023

A Large Proportion of Crime Goes Unsolved in California

photo - police car with yellow barrier tape

Amid widespread concerns about crime and the efficacy of the police, what do we know about how many crimes are solved across California? To get at that question, researchers use a measure called the clearance rate—the share of reported crimes for which police make an arrest and refer the arrestee to prosecution. We find that today, less than half of violent crimes in California are cleared. For property crimes, only one in ten reported incidents leads to an arrest. While California’s rates are better than those nationwide, an unsettling proportion of crime in our state goes unresolved.

Clearance rates are a key measure of police efficacy, which has come under intense scrutiny in recent years. In California, the number of law enforcement officers in the state has declined notably, plausibly resulting in fewer officers to solve crimes; furthermore, research has found that greater police staffing helps to prevent crime.

But clearance rates have additional, important implications—including a sense of justice for victims, public perceptions of accountability, and the potential for crime deterrence. Community trust in law enforcement is likely affected by the ability of police to solve crime. At the same time, lack of trust may diminish agencies’ ability to do so.

Here we take a look at how clearance rates have changed over the last few decades, examining these rates by type of offense. Our data comes from the California Department of Justice’s crimes and clearance data, and covers 1985–2020. (While data for 2021 is available, we do not include it here, as crimes reported at the end of that year do not provide law enforcement the same amount of clearance time as in previous years.)

In 2020, about 45% of reported violent crimes in California were solved. While this clearance rate has fluctuated somewhat, peaking at slightly above 50% in the late 1990s, it has stayed within a relatively narrow band over the last decade and is roughly where it was in the late 1980s.

Close to two thirds of homicides were solved, up from about half in the early 2000s, and well above the declining national rate of 50%. Slightly more than half of reported aggravated assaults incidents were cleared. While over the last decade this rate has stayed relatively constant, it is below the roughly 60% in the 1980s and 1990s, but somewhat higher than the national rate of 47%.

The share of reported rapes that have been solved has declined since the late 1990s, when it was around 50%; in 2020, it was 35%. In contrast, for robbery—property stolen by use or threat of force—the clearance rate, has increased over the last decade, from about 25% to 33%. Both of these rates are above the national clearance rates of 30% and 27% respectively.

figure - More than half of homicides and aggravated assaults are solved, but only one out of three rapes and robberies

Markedly lower shares of reported property crimes are solved. The clearance rate has been dropping notably since 2014 and is below the national rate. Overall, only 9% of reported property crimes are cleared. This clearance rate has been decreasing since the early 1990s, when it was 17%.

About 12% of burglaries—unlawful entry of residential or commercial structures—are solved, remaining within a relatively narrow band of 12% to 14% since 1985. The clearance rate for auto theft has increased somewhat over the last decade, from around 7% to about 10% in most recent years—but this rate is lower than the 14%–15% of the mid 1980s.

The most notable decrease is for larcenies— theft of property without the use or threat of force —which dropped from about 21% in 1990 to 9% in 2020. This shift may partly stem from the passage of Proposition 47 in 2014, which reclassified a number of drug and property offenses from felonies to misdemeanors. Driven by car break-ins, larceny increased immediately in the proposition’s wake, while arrest rates for property crimes simultaneously decreased.

If, as is plausible, car break-ins are quite challenging to solve, the fact that they made up an increasing share of larcenies between 2014 and 2020 may also have contributed to the decline in larceny clearance rates. Fewer arrests for larcenies in the wake of Prop 47 may also reflect the stricter arrest criteria for misdemeanors than felonies, including that in most instances the crime must take place in the presence of a police officer.

figure - Driven by larcenies, clearance rates for property crimes have been decreasing since 2014

It is encouraging to see that California law enforcement prioritizes more serious crimes in their efforts to bring justice to victims, and that the state has higher clearance rates than the nation overall. But the data points toward an unsettling share of both violent and property crimes with no resolution. While the pandemic undoubtedly presented challenges to making arrests and solving crimes, the arguably low clearance rates may be contributing factors to Californians increasingly expressing concerns about crime and law enforcement’s ability to control crime.

While the data examined here does not allow for determining race/ethnicity of the victims, research has found lower clearance rates involving victims of color. Better understanding of how higher shares of crime can solved is essential—as is identifying what the current barriers are (declining numbers of police officers may play a role, as may the reduction in DNA collection as a result of Prop 47). More clarity on these critical issues may very well help to improve trust and confidence in law enforcement across California’s communities.


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