California is conducting an immense sociological experiment, testing whether reducing prison time for criminal acts will, in the long run, mean less crime.

Over the last decade, politicians and voters have lowered penalties for dozens of serious and minor crimes, reduced state prison populations by about 40% and adopted multiple programs to treat underlying conditions, such as drug use and lack of education, to deter offenders from committing new crimes.

It’s been a dramatic turnaround from previous decades, when the public demanded ever-tougher sentences and the state couldn’t build prisons fast enough to handle a tidal wave of new inmates, resulting in overcrowding so severe that federal judges intervened.

The change coincided with California’s equally dramatic political reorientation.

From the late 1970s to the early 1990s, a fear of crime, particularly violent crime, dominated the state’s political atmosphere, symbolized by the “three strikes and you’re out” law aimed at putting repeat felons behind bars for life.

Republicans adroitly capitalized to win elections by accusing Democratic rivals of being soft on crime. In 1986, voters overwhelmingly voted out three liberal state Supreme Court justices because of their capital punishment rulings.

Republican overreach, particularly a ballot measure targeting undocumented immigrants, and complex economic and sociological factors, such as the collapse of Southern California’s aerospace industry, began changing the state’s political climate in the late 1990s.

Within a decade, Democrats had achieved dominance at all levels and soon embraced what they called “criminal justice reform.”

Jerry Brown, who experienced the political impact of crime as governor in the late 1970s and 1980s and signed some of the lock-‘em-up bills, returned to the governorship in 2011. He was bent on reversing course, but cautiously didn’t make that intent public until he had won a fourth and final term in 2014.

Brown sponsored a 2016 ballot measure, Proposition 57, that swept away much of what he and other governors had wrought decades earlier, with political cover from federal judges who had ordered reductions in prison populations due to overcrowding.

Brown’s successor, Gavin Newsom, is continuing the experiment. Even though the death penalty is still law, Newsom has declared an execution moratorium. He also accelerated reductions in prison populations because of severe COVID-19 outbreaks and promised to close prisons.

Newsom’s proposed 2021-22 budget projects that the prison population, once as high as 170,000, will drop to 97,950 this year and continue declining thereafter.

Meanwhile, voters in San Francisco and Los Angeles have elected new district attorneys on platforms to minimize incarceration and maximize diversions into non-penal rehabilitation.

They are seeing some pushback. George Gascón, who had been San Francisco’s district attorney before shifting to Los Angeles, is even being sued by his own deputies, contending he is violating the law by ordering them to seek minimal sentences for crimes.

The bottom line question, of course, is whether the attitudinal change will, as advocates contend, reduce the system’s disproportionate impact on Black and Latino communities while also reducing the overall threat of crime.

Interestingly, and perhaps significantly, violent crime has been spiking upwards during the nearly year-long COVID-19 pandemic. This month, Los Angeles Police Chief Michel Moore cited a sharp surge in homicides in his city to more than 300 in 2020 and 24 in the first two weeks of 2021.

In mid-January, the Los Angeles Times’ running tally of homicides counted 656 in Los Angeles County during the previous 12 months.

“It’s our shared responsibility to stop this senseless violence,” Moore said in his tweet.

If, however, it continues, will crime once again become a burning political issue?

Dan Walters is a CalMatters columnist.