In rare displays of bipartisanship, state legislative coalitions of liberal Democrats and conservative Republicans are overhauling sentencing procedures and making other important changes in criminal justice laws.

Legislatures in Alabama and Maryland last month passed laws that will shorten many prison terms, while the Massachusetts Legislature is mulling a measure that would abolish mandatory minimum sentences.

The Alabama law reduces sentences for nonviolent property and drug crimes, and was hailed by Republican Gov. Robert Bentley  as “a significant step forward to address reform of Alabama’s criminal justice system.”

The Maryland law allows courts in most cases to depart from mandatory minimum sentences, a practice favored by many judges. Republican Gov. Larry Hogan, who had vetoed a more far-reaching bill, let it become law without his signature.

These new laws continue a trend that began several years ago, partly in response to prison overcrowding. Democrats and Republicans in 29 states have cooperated on legislation easing mandatory minimum sentences.

In some states they’ve also increased use of parole and halfway houses and limited civil asset forfeiture. Colorado, Kentucky, New Mexico and the District of Columbia have made it easier to obtain bail, which disproportionally burdens the poorest defendants.

On occasion, the left-right alliance extends to the emotional issue of capital punishment.

Staunchly conservative Nebraska last month became the 19th state to abolish the death penalty. Although Nebraska’s unicameral Legislature is nominally nonpartisan, a majority of legislators are Republicans.

One of them, Sen. Colby Coash, R-Lincoln, said to The Economist: “We would have ended any other government programs that inefficient and costly a long time ago.”

The Nebraska Legislature repealed the death penalty over the veto of Republican Gov. Pete Ricketts, who said it should be kept as a matter of public safety. He claimed, probably accurately, that a majority of Nebraskans agreed with him.

According to the Gallup polling organization, six in 10 Americans favor the death penalty, a support level largely unchanged in the last 20 years.

But states use it less and less. In addition to Nebraska, five states — Connecticut, Illinois, Maryland, New Jersey and New Mexico — have abolished the death penalty since 2007. Only seven states conducted executions in 2014.

The situation in California, where 850 inmates are on death row and no executions have occurred in nine years, frustrates those on both sides of the death penalty debate.

Opponents of capital punishment have failed repeatedly in attempts to abolish it — voters last rejected such an attempt in 2012 by a 52 percent to 48 percent margin — while advocates worry that the death penalty has lost deterrent value because executions are so infrequent.

Because of protracted appeals and the difficulty of finding drugs for lethal injection that can pass legal muster, California has executed only 13 people since 1978. During that time, another 101 people have perished on death row, most of them from natural causes.

While capital punishment remains ideologically divisive in many states, there is growing consensus across the political spectrum that lengthy prison sentences for drug users and other nonviolent offenders are of dubious value.

Such sentences are particularly a concern in African-American communities. Thirty-seven percent of those in state or federal prisons are non-Hispanic blacks, according to the Justice Department. Blacks are six times as likely as whites to be imprisoned.

With more than 2.2 million inmates in federal and state prisons and county jails, the United States has the largest prison population of any developed country. But for much of the 20th century, U.S. imprisonment rates were comparable to the rest of the world, according to Michael Stoll, a UCLA professor of public policy.

The U.S. prison population exploded in the 1970s, fueled by politicians who exploited public fear of crime by passing “two strikes” and “three strikes” laws to keep repeat offenders behind bars.

Congress also encouraged longer incarcerations by giving states financial incentives to pass “truth-in-sentencing” laws requiring those convicted to serve at least 80 percent of their sentences.

Most significant, the federal government and many states replaced indeterminate sentences, in which judges could consider mitigating factors, with mandatory minimums that eliminate judicial discretion.

States began to have second thoughts, however, as overcrowded prisons required the building of expensive new facilities. The U.S. Supreme Court found in a 2011 case, Brown v. Plata, that inadequate health care in severely crowded California prisons was constitutionally impermissible. The decision forced the state to come up with a plan that released some prisoners and transferred thousands of others into county jails already bursting at the seams.

Longer prison sentences have at best a tenuous relationship to public safety. Crime rates rose in some states with longer sentences and fell in some states with shorter ones. A recent report by the Brennan Center for Justice at New York University found that the effect on the crime rate of increased incarceration during the last 15 years “has been effectively zero.”

Starting in the late 1990s, falling crime rates made the public more receptive to prison reform. The reasons for the falloff are inconclusive, but the data is dramatic.

Between 1994 and 2012 violent crime in the United States dropped to 387 per 100,000 persons from 713. The murder rate was more than halved.

The homicide decline was especially notable in some of the nation’s largest cities: New York City murders fell to 328 in 2014 from 2,397 in 1992, while Los Angeles murders declined to 260 from 1,092.

The tidy narrative of bipartisanship on prison reform is that Republican legislators became alarmed by soaring prison costs while their Democratic counterparts responded to the damage being wreaked on minority communities by long imprisonments.

This is a stereotypical view. Many Republicans as well as Democrats expressed humane concerns about the plight of minor offenders, especially substance abusers who received little help in prison. Members of both parties were troubled that rising prison costs impinged on funding for education.

Leadership on prison reform sometimes came from unlikely places.

“South Carolina is usually the first of everything bad and last in everything good,” state Sen. Gerald Malloy, D-Darlington, declared in 2010 after a Republican governor signed into law a prison-reform bill introduced by Malloy and passed by a GOP-controlled Legislature.

Not in this instance. The law reduced sentences for many crimes and cut South Carolina’s prison population so much that the state in February announced the closure of its second maximum-security prison in a year.

Other Southern and border states followed suit.

In 2011, Kentucky lessened penalties for drug crimes and steered users to rehabilitation programs. Georgia reformed its adult and juvenile prisons systems in 2012 and 2013, giving judges leeway in sentencing and increasing prison oversight. Mississippi passed a law in 2014 providing alternatives to prison for drug offenders.

The biggest falloffs in prison populations occurred in California, New Jersey and New York, states in which violent crime rates also declined more than the national average.

According to The Sentencing Project, a Washington-based think tank, prison populations in both New Jersey and New York fell 26 percent from 2006 through 2012. California’s prison population declined 23 percent.

Six other states — Colorado, Connecticut, Hawaii, Michigan, Rhode Island and Vermont — posted double-digit reductions in prison populations during these years.

But it’s too early for reformers to engage in self-congratulation. Prison populations in many states remain higher than they were two decades ago when crime was rampant.

The data on federal inmates — updated online weekly by the Federal Bureau of Prisons — is particularly instructive. As of June 11, there were 208,388 federal inmates, down slightly from a year ago but nearly nine times more than the 24,060 inmates that were in federal prisons in 1980 when this database began.

In most states, despite improvements, there are still limited resources for treating substance abusers and even less help for the mentally ill.

A May report by the Pew Charitable Trusts found that “many jails across the country hold more mentally ill people than hospitals do.” The plight of the mentally ill is the topic for another essay; suffice here to say that it’s deeply entwined with criminal justice issues, including prison reform.

Under the headline, “Being Smart on Crime and Safety,” a new UCLA publication called Blueprint, edited by Jim Newton, former editorial page editor at the Los Angeles Times, sounded a clarion call for an enlightened approach to sentencing.

“Policymakers are understandably skittish about being seen as coddling criminals,” he wrote, “but if the cost of sounding tough is a society that is less safe and more racially divided, then it seems like a high and foolish price to pay.”

Lou Cannon, a Summerland resident, is a longtime national political writer and acclaimed presidential biographer. His most recent book — co-authored with his son, Carl — is Reagan’s Disciple: George W. Bush’s Troubled Quest for a Presidential Legacy. Cannon also is an editorial adviser to State Net Capitol Journal, which published this column originally. Click here to read previous columns. The opinions expressed are his own.

Lou Cannon, State Net Capitol Journal

Lou Cannon, a Summerland resident, is a longtime national political writer and acclaimed presidential biographer. His most recent book — co-authored with his son, Carl — is Reagan’s Disciple: George W. Bush’s Troubled Quest for a Presidential Legacy. Cannon also is an editorial adviser to State Net Capitol Journal, which published this column originally. Click here to read previous columns. The opinions expressed are his own.