California voters’ decision to reduce penalties for drug and property crimes in 2014 contributed to a jump in car burglaries, shoplifting and other theft, researchers reported.

Larcenies increased about 9% by 2016, or about 135 more thefts per 100,000 residents than if tougher penalties had remained, according to results of a study by the nonpartisan Public Policy Institute of California released Tuesday.

Thefts from motor vehicles accounted for about three-quarters of the increase. San Francisco alone recorded more than 30,000 auto burglaries last year, which authorities largely blamed on gangs. Shoplifting may be leveling off, researchers found, but there is no sign of a decline in thefts from vehicles.

Proposition 47 lowered criminal sentences for drug possession, theft, shoplifting, identity theft, receiving stolen property, writing bad checks and check forgery from felonies that can carry prison terms to misdemeanors that often bring minimal jail sentences.


Though researchers can link the measure to a rise in theft, they found it did not lead to the state’s increase in violent crime.

Violent crime surged by about 13% after Proposition 47 passed, but researchers said the trend started earlier and was mainly linked to unrelated changes in crime reporting by the FBI and the Los Angeles Police Department.

The FBI broadened its definition of sexual crimes in 2014, while the LAPD improved its crime reporting after previously underreporting violent crimes. If it weren’t for those changes, researchers found, California’s violent crime rate would have increased 4.7% from 2014 to 2016.

Researchers compared California’s crime trends to those in other states with historically similar trends. They found the increase in California’s violent crime rate was less than that of comparison states, but larcenies jumped in California as they declined elsewhere.


California still has historically low crime rates despite recent changes in the criminal justice system aimed at reducing mass incarceration and increasing rehabilitation and treatment programs, said Lenore Anderson, the executive director of Californians for Safety and Justice and a leader in the drive to pass Proposition 47.

“This report shows we are making progress,” she said in a statement calling for less spending on prisons and more on programs to help reduce the cycle of crime.

The ballot measure led to the lowest arrest rate in state history in 2015 as experts said police frequently ignored crimes that brought minimal punishment.

Jail bookings in 12 sample counties dropped about 8%, driven by a reduction in bookings for Proposition 47 crimes, while cite-and-releases increased, researchers found.


Offenders convicted of those crimes were about 3% less likely to be convicted of a new crime within two years, but the researchers said it’s not clear if that was because they didn’t commit new crimes or because they were less likely to be arrested and prosecuted due to the lower penalties.

Reduced penalties mean that fewer drug addicts seem to be getting treatment and then “are stealing to support their habit,” said San Luis Obispo County Chief Probation Officer Jim Salio, president of the Chief Probation Officers of California.

Morgan Hill Police Chief David Swing, president of the California Police Chiefs Assn., said researchers’ findings “are consistent with what police chiefs across the state have seen since 2014” and show the need for a proposed initiative intended for the November ballot that would partly roll back the 2014 law.

It would allow prison sentences for serial thieves, reinstate DNA collections from those convicted of the crimes for which penalties were reduced, and bar the earlier release of criminals convicted of additional violent, serious and sexual crimes.