An inmate looks out from his cell at Corcoran State Prison in Corcoran, Calif. (Robert Galbraith/Reuters)

Charis E. Kubrin and Carroll Seron are professors of criminology, law and society in the School of Social Ecology at the University of California at Irvine. Joan Petersilia is a professor at Stanford Law School.

In an era of bitter partisanship, politicians and pundits across the ideological spectrum seem to agree on one thing: Our prison system is broken. With less than 5 percent of the world’s population yet nearly 25 percent of the world’s prison inmates, the United States spends too much money locking up too many people for too long.

Some fear that reducing sentences for nonviolent crimes and letting low-level offenders back on the streets — key components of prison reform — could produce a new and devastating crime wave. Such dire predictions were common in 2011 when California embarked on a massive experiment in prison downsizing.

But five years later, California’s experience offers powerful evidence that no such crime wave is likely to occur.

In 2011, the Supreme Court ruled that California’s wildly overcrowded prisons were tantamount to cruel and unusual punishment and ordered the state to reduce its prison population by some 33,000 people in two years. In response, the state enacted the controversial California Public Safety Realignment law , known in legislative shorthand as AB 109.

With a budget of more than $1 billion annually, “realignment” gave each of the state’s 58 counties responsibility for supervising a sizable class of offenders — the “triple nons,” or non-serious, nonviolent, non-sex offenders — formerly housed in state prisons. Each county received unprecedented flexibility and authority to manage this population as it saw fit.

Recently, we brought together a group of distinguished social scientists to do a systematic, comprehensive assessment of California’s prison downsizing experiment. The results, published this month in the Annals of the American Academy of Political and Social Science, show that California’s decision to cede authority over low-level offenders to its counties has been, for the most part, remarkably effective public policy and an extraordinarily rich case study in governance.

There has been great variation in how counties have dealt with their newfound authority. Some have decided essentially to continue with the status quo, placing offenders into local jails. Other counties have experimented with innovative reforms such as new reentry and rehabilitation programs to ease the transition of convicts back into the community.

To answer questions about the relationship between prison reform and crime rates, we not only compared statewide crime rates before and after the downsizing but also examined what happened in counties that favored innovative approaches vs. those that emphasized old-fashioned enforcement.

Clearly, our most important finding is that realignment has had only a very small effect on crime in California.

Violent crime rates in the state have barely budged. We’ve seen no appreciable uptick in assaults, rapes and murders that can be connected to the prisoners who were released under realignment. This makes a lot of sense when you think about it; by and large, these offenders were eligible for release because of the nonviolent nature of their crimes.

On the other hand, a small uptick in property crime can be attributed to downsizing, with the largest increase occurring for auto theft. So is this an argument against realignment and against prison reform more broadly?

We think not. The cost to society of a slight increase in property crime must be weighed against the cost of incarceration. Take the example of auto theft. Our data suggest that one year served in prison instead of at large as a result of realignment prevents 1.2 auto thefts per year and saves $11,783 in crime-related costs plus harm to the victims and their families. On the other hand, keeping someone behind bars for a year costs California $51,889. In purely monetary terms — without considering, say, the substantial economic and social hardship that imprisonment can create for prisoners’ children and other relatives — incarcerating someone for a year in the hope of preventing an auto theft is like spending $450 to repair a $100 vacuum cleaner.

Turning to the question of which counties’ strategies were most successful, we have another important early finding: Counties that invested in offender reentry in the aftermath of realignment had better performance in terms of recidivism than counties that focused resources on enforcement.

As other states and the federal government contemplate their own proposals for prison downsizing, they should take a close look at what these California counties are doing right.