A ground breaking study of who actually gets arrested in four California metropolitan areas has some surprising results. It’s us. Okay, maybe not you or me individually, but almost 80 percent of the people arrested in Sacramento, Redlands, Los Angeles and San Francisco over a three and a half year period were not on probation or parole at the time of their arrest.

The Council of State Governments Justice Center conducted the study at the request of the police chiefs from the four cities, an effort that involved the review of more than 2.5 million arrest records. People on parole and probation account for only about 1-in-5 arrests. Only one in six people arrested for violent crimes were on probation or parole, but one in three of people arrested for drug crimes were under supervision. The study period was before the 2011 “realignment” that shifted low-level state-supervised offenders to county supervision. However, it appears that concerns about parolees and probationers driving arrest rates are unfounded.

The study also found that evidence-based risk assessment tools can be remarkably accurate in determining who is most likely to reoffend. These tools can help law enforcement agencies get more bang for their buck. There is little value in supervising someone who has only minimal risk for creating additional problems. Conversely, higher risk offenders can either be provided with substance abuse programs, job training, and other programs that reduce their likelihood of reoffending, or be monitored so closely they do not have the opportunity to reoffend.

That seems to be working in San Francisco, according to Chief Probation Officer Wendy Still, quoted in the Chronicle: “We have changed our supervision strategy from supervising by type of case to by risk level,” she said. “And it’s remarkable – during the first year of realignment, 60 percent of (people being released from state prison) were compliant with the terms of their supervision, as compared to (state) parole where they had a 70 percent failure rate.”

The study also indicates that there is a need for additional research across broader geographic and socio-economic parameters. That assessment will require sharing more information and a willingness to participate in the process. Grant money paid for this initial study, but additional work may come with a price tag. Given what we know about the costs of incarceration, additional information that helps keep people out of jail and still provides for public safety is probably a good investment.