For the past year, President-elect Donald Trump campaigned on “law and order,” stating at the Republican National Convention that under a Trump presidency, “safety would be restored.” His administration, with Sen. Jeff Sessions as attorney general, is likely to be unfriendly on criminal justice. However, Trump and his ilk are outliers. There is strong trans-partisan agreement, among politicians, law enforcement, advocates and researchers that there are simply too many people in prison.

Crime exploded in the 1980s and 90s. Officials responded with harsh sentencing laws that had little impact and ironically may have made things worse. Now that crime is down, we need to change our approach. Instead of doubling down on the failed draconian policies of the past, based on vengeance, we have an opportunity to rethink how America punishes people who break the law and ground those decisions in what we know works.

With 2.2 million people in prison, mass incarceration is the greatest moral and racial injustice of our time. We need bold solutions to solve this crisis, but few systemic solutions exist.

For the past three years, we led a team of criminologists, lawyers, and statistical researchers to analyze criminal codes, convictions, and sentences to help pave a way forward. This week, we released our findings in a new report, How Many Americans Are Unnecessarily Incarcerated?

We found that approximately 39% of the nationwide prison population (576,000 people) is behind bars with little public safety rationale. And they can be released, significantly and safely cutting our prison population.

How did we get to this number? First, many people who are in prison shouldn’t have been sent there in the first place. For example, we found that 25% of prisoners (364,000 people), almost all non-violent, lower-level offenders, would be better served by alternatives to incarceration such as treatment, community service, or probation. Second, another 14% (212,000 prisoners) have already served long sentences for more serious crimes and can be safely set free.

Releasing these inmates would save $20 billion annually, enough to employ 270,000 new police officers, 360,000 probation officers, or 327,000 school teachers.

Republicans and Democrats agree that America’s experiment in mass incarceration has failed. Our research-driven recommendations aim to help rethink sentencing to make our justice system better by decreasing crime and recidivism, reducing the disproportionate impact on communities of color, and preserving the hard-won declines in crime over the last 20 years.

How We Got Here

There was a period in America where crime dominated the headlines. In 1968, Republican presidential candidate Richard Nixon ran a campaign commercial where a series of still photos of angry protesters and burning buildings appeared over a soundtrack of a snare drum and dissonant piano chords. “Let us recognize that the first civil right of every American is to be free from domestic violence,” Nixon intoned. “So I pledge to you, we shall have order in the United States.” To a large extent, what average Americans saw on their television screens squared with their own experiences. From 1960 to 1980, violent crime soared 270%, peaking at 758 violent offenses per 100,000 people in 1991. African American and Latino communities bore the brunt of this crime rise. By the late 1970s, people of color were crime victims at a rate 24% higher than white Americans.

States and the federal government responded by enacting a series of laws that dramatically lengthened sentences for many crimes, and also created entirely new ones. Increased policing of lower-level offenses and drug violations swept more individuals into the system. Punitive policies such as mandatory minimum sentencing, the abolishment of parole, and a slew of new criminal laws caused the prison population to explode.

The nation experienced a prison boom. Average lengths of time behind bars increased by 33% in state prisons between 1993 and 2009, and doubled in the federal system.

As America became the world’s number one jailer, crime plummeted dramatically. Today, the overall crime rate is half of what it was at its peak in 1991. Violent crime is about where it was in 1970. Property crime is at 1967 levels.

Many may assume that this decrease in crime was caused by the increase in incarceration. But research shows incarceration had a limited impact on the massive drop in crime.

“When the incarceration rate is high, the marginal crime reduction gains from further increases tend to be lower, because the offender on the margin between incarceration and an alternative sanction tends to be less serious,” according to the Brookings Institute’s Hamilton Project. “In other words, the crime fighting benefits of incarceration diminish with the scale of the prison population.” A 2015 Brennan Center study came to the same conclusion.

Although there is some relationship between increased incarceration and lower crime, at a certain point, locking up additional people is not an effective crime control method, especially when imprisoning one person costs $31,000 a year.

Building on State Successes

The current sentencing regime was largely a knee-jerk reaction to crime, not grounded in any scientific rationale. While it may have seemed like a reasonable approach to protect the public, a comprehensive examination of the data proves it is ineffective at that task. Worse yet, it is also inequitable, placing a disproportionate burden on communities of color. Whether viewed through a lens of justice, fairness, public safety, cost, or victims’ rights, the U.S. prison system unnecessarily warehouses millions of people.

There are some state models for success. Over the last decade, a majority of states reduced their prison populations while cutting crime. From 1999 to 2012, New Jersey and New York reduced their prison populations by about 30%, while crime fell faster than it did nationally. Texas decreased imprisonment and crime by more than 20% during the same period. California cut its prison population by 27%, and violence in the state also fell more than the national average. These state reforms are excellent steps in the right direction. They provided modest fixes and short term relief. Although these reforms are heartening, we need more wholesale systemic changes to strike a blow to mass incarceration.

A problem of such epic proportions needs a bold solution.

Who’s Unnecessarily Behind Bars

Our team discovered these 576,000 people by rethinking who really needs to be behind bars and whether an alternative to prison could be a more effective sentence. Our current sentencing regime is largely based on outdated ideas about what is necessary to keep the nation safe, which we know don’t work.

Public safety should be the number one reason we incarcerate. But penalties should be the most effective, proportional, and cost-efficient sanction to achieve that goal. This would create more uniform sentences and reduce disparities, while preserving judicial discretion when needed.

To arrive at our findings, we considered four major factors.

The first factor is seriousness. Murder, for instance, should be treated as a far graver crime than writing a bad check. The second is victim impact. If a person has been harmed in the commission of a crime, especially physically, the punishment should weigh toward a more serious sentence. The third factor is intent. If a person knowingly and deliberately violated the law, a more severe sanction may be appropriate. The fourth factor is recidivism. Those more likely to reoffend may need more intervention.

We first applied this analysis to people convicted of lower-level offenses. We found that for an estimated 364,000 lower-level offenders (25% of the nationwide prison population), alternatives to prison are likely more effective.

We then applied these factors to prisoners who were serving serious crimes. They may warrant prison, but do they really need such lengthy sentences?

Research shows long sentences aren’t very effective. A 2007 National Bureau of Economic Research study found that prison stays longer than 20 months had “close to no effect” on reducing commission of certain crimes upon release. Other studies show prison often has a “criminogenic” effect, meaning that imprisonment can actually lead people to commit more crimes after release.

With that in mind, we took the 58% of prisoners serving time for six major crimes — aggravated assault, murder, nonviolent weapons crimes, robbery, serious burglary, and serious drug trafficking — and tested several methods for cutting sentences, ultimately landing on a 25% reduction. This approach would ensure that sanctions for serious crimes involve significant prison time, but that the sentences are better calibrated to deter recidivism and protect public safety.

This approach would shave a little over a year from prison sentences for these crimes. Applied retroactively, it means 212,000 prisoners (14% of the total prison population) have already served sufficiently long prison terms and could be released within the next year with little risk to public safety.

Rethinking Sentencing in America

Our findings are not isolated. A prominent coalition comprised of groups such as the ACLU, Beyond the Dream, #Cut50, Ella Baker Center, #FreeAmerica, and JustLeadershipUSA is calling for the prison population to be cut by 50%. Other criminologists have recommended we go back to the sentencing regime of the 1970s and 1990s, which would require us to cut average prison stays by almost 40%.

Our recommendations are more conservative and err on the side of public safety. We recommend that state legislatures and Congress make two major changes to sentencing laws: (1) eliminate prison for lower-level crimes altogether, barring exceptional circumstances; (2) and reduce current sentence lengths to be more proportional to the crimes committed, starting with considering a 25% cut to the six crimes we tested. We also recommend that they allow current prisoners to petition for application of these news laws, and that prosecutors use their discretion to seek sentences in line with this report.

Judges should have discretion to depart from these guidelines in special circumstances. And, we can’t simply swing open the prison doors — prisoners need proper support upon reentry into society to ensure they get back on their feet and do not recidivate.

Sentences should be based on what works to prevent crime, not vengeance. On social science research, not conjecture from 30 years ago on what we mistakenly assumed worked. And sentences should be proportional to the crime committed.

What Now?

Donald Trump campaigned on a message that Washington is broken. Our bloated, wasteful, ineffective, and unnecessarily harsh criminal justice system is a prime example of that. Republicans like House Speaker Paul Ryan, Senators Mike Lee and John Cornyn, and even Vice President-elect Mike Pence and Newt Gingrich have strongly backed criminal justice reform. In fact, many efforts in the states were championed by conservative lawmakers.

Republicans should not walk away from the cause now that Trump is in the White House. Their voices will be crucial in explaining to the next administration why America’s experiment in mass incarceration has failed, and needs to be fixed. Not only does using prison as a one size fits all punishment for crime devastate families and communities, but many of today’s overly punitive prison sentences produce little public safety benefits.

Our findings and recommendations are intended to offer a practical and effective approach to end mass incarceration while preserving public safety. Our goal with this report is to jump-start a conversation about how the United States can implement specific reforms that are audacious enough to truly end mass incarceration.

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