Seychelles, a group of 115 islands off the east coast of Africa with 92,000 residents, does not figure prominently on many lists, but it leads the world in locking people up. It is the only country with a higher incarceration rate than the United States.

If the reforms recommended in a new report from the Brennan Center for Justice were fully implemented, the U.S. would fall from second to fourth place on that list—behind Seychelles, St. Kitts and Nevis, and Turkmenistan, but still far ahead of every other liberal democracy, not to mention Iran, Saudi Arabia, and Zimbabwe. The report is nevertheless an admirable effort to grapple with the morally and fiscally pressing question of who belongs behind bars and who doesn't.

Between 1974 and 2007, the U.S. imprisonment rate (excluding people in local jails) soared from 102 to 506 per 100,000, thanks to changes in sentencing (including mandatory minimums and "three strikes" laws), parole (including "truth in sentencing" laws), and prosecutorial practices (including an increased tendency to bring charges). Since 2007 the imprisonment rate has declined a bit, but it is still more than four times as high as in the mid-1970s.

This imprisonment binge was largely a response to crime rates, which rose dramatically from the 1960s until the early '90s, when they began a long slide. Today the violent and property crime rates are half what they were in 1991.

Although "it is tempting to look at these data and assume that mass incarceration caused this decline in crime," the Brennan Center says, research suggests imprisonment played a modest role that shrank over time. It turns out that increases in the number of people behind bars and the amount of time they spend there yield diminishing returns.

In recent years, states such as California, Texas, New York, and New Jersey have seen crime rates continue to fall while substantially reducing their prison populations. The trick is figuring out which offenders can remain free and which prisoners can be released without compromising public safety. Prison should be reserved for the most serious offenders, and longer sentences are not necessarily better, especially in light of evidence that they do not enhance deterrence and may actually increase recidivism.

The Brennan Center argues that alternatives to incarceration, such as community service, electronic monitoring, restitution, and drug treatment, are generally appropriate for "lower-level crimes" such as minor drug offenses, minor property crimes, simple assault, and "lesser burglary" (involving unoccupied structures and no direct contact with victims). About 364,000 current prisoners fall into this category.

The report also recommends default sentences for half a dozen more serious crimes that are 25 percent shorter than current sentences. That change would reduce the average sentence for "serious burglary" from 1.7 to 1.3 years, for aggravated assault and nonviolent weapon offenses from 3 to 2.3 years, for drug trafficking from 3.4 to 2.6 years, for robbery from 4.2 to 3.1 years, and for murder from 11.7 to 8.8 years.

Since average time served in state prisons rose by 33 percent between 1993 and 2009, a 25 percent reduction would make state sentences about as long as they were in the early 1990s. Applying the reduction to current prisoners would allow 212,000 to petition for release. The Brennan Centers recommends that judges decide who should be freed on a case-by-case basis, taken into account the expected impact on public safety.

It costs taxpayers $31,000 a year to keep someone in prison. Releasing the 576,000 prisoners in the two categories identified by the Brennan Center, who represent two-fifths of the prison population, therefore would save about $18 billion a year, a quarter of state and local spending on corrections.

Indiscriminate incarceration and disproportionate penalties cost more than taxpayer money. They impose heavy, long-lasting burdens on offenders, their families, and their communities, all without enhancing public safety. That wasteful injustice can be corrected only if legislators are willing to rethink who goes to prison and why.

© Copyright 2016 by Creators Syndicate Inc.