In the United States, murders have plummeted in the last 20 years, as has crime. A culture that in the 1980s was commonly projected to be morphing into gangs of youth wilding across urban areas has become just the opposite. Even New York City is reasonably safe.

But one thing has risen dramatically while crime has dropped; incarceration. 

Now, a group of scholars is saying jail has little to do with crime rate or prevention and they further believe that the negative social consequences (harder to get a job, can't buy a gun, can't vote) and cost of incarceration means we should open some cell doors.

The National Research Council review concluded that the costs of the current rate of incarceration outweighs the benefits. The committee recommended that federal and state policymakers re-examine policies requiring mandatory and long sentences, as well as take steps to improve prison conditions. In addition, it recommends a reconsideration of drug crime policy,which accounts for a lot of incarcerations. Colorado, for example, has legalized marijuana but has thousands in its jails for marijuana possession.

"We are concerned that the United States is past the point where the number of people in prison can be justified by social benefits," said committee chair Jeremy Travis, president of John Jay College of Criminal Justice in New York City. "We need to embark on a national conversation to rethink the role of prison in society. A criminal justice system that makes less use of incarceration can better achieve its aims than a harsher, more punitive system. There are common-sense, practical steps we can take to move in this direction."

The unprecedented and internationally unique rise in U.S. state and federal prison populations, from 200,000 inmates in 1973 to 1.5 million in 2009, occurred because of policy decisions such as mandatory sentencing, long sentences for violent and repeat offenses, and intensified criminalization of drug-related activity. Stricter sentencing policies were formed initially during a period of rising crime and social change; however, over the four decades when incarceration rates rose steadily, crime rates fluctuated.

The committee evaluated scientific evidence on the effects of high incarceration rates on public safety and U.S. society, as well as their effects on those in prison, their families, and the communities from which prisoners originate and to which they return. The following data illustrate the magnitude of incarceration rates, the racial disparities of incarceration, and societal impacts:

• With the inclusion of local jails, the U.S. penal population totals 2.2 million adults, the largest in the world; the U.S. has nearly one-quarter of the world's prisoners, but only 5 percent of its population.

• Nearly 1 in 100 adults is in prison or jail, which is 5 to 10 times higher than rates in Western Europe and other democracies.
• Of those incarcerated in 2011, about 60 percent were black or Hispanic.
• Black men under age 35 who did not finish high school are more likely to be behind bars than employed in the labor market.
• In 2009, 62 percent of black children 17 or younger whose parents had not completed high school had experienced a parent being sent to prison, compared with 17 percent for Hispanic children and 15 percent for white children with similarly educated parents.

Another major consequence of high rates of incarceration is their considerable fiscal burden on society, the report says. Allocations for corrections have outpaced budget increases for nearly all other key government services, including education, transportation, and public assistance. State spending on corrections is the third highest category of general fund expenditures in most states today, ranked only behind Medicaid and education.

Estimating incarceration's impact on crime is challenging, and studies on this topic have produced divergent findings. However, the report concludes that the increase in incarceration may have caused a decrease in crime, but the magnitude of the reduction is highly uncertain and the results of most studies suggest it was unlikely to have been large. In addition, the deterrent effect of increases in lengthy prison sentences is modest at best. Because recidivism rates decline significantly with age, lengthy sentences are an inefficient approach to preventing crime, unless they can specifically target high-rate or extremely dangerous offenders.

People who live in poor and minority communities have always had substantially higher rates of prison admission and return than other groups. Consequently, the effects of harsh penal policies in the past 40 years have fallen most heavily on blacks and Hispanics, especially the poorest, the report says. In 2010, the imprisonment rate for blacks was 4.6 times that for whites. This exceeds racial differences for many other common social indicators, from wealth and employment to infant mortality.

Incarceration correlates with negative social and economic outcomes for former prisoners and their families, and it is concentrated in communities already severely disadvantaged and least capable of absorbing additional adversities. From 1980 to 2000, the number of children with incarcerated fathers increased from about 350,000 to 2.1 million — about 3 percent of all U.S. children. Further, men with a criminal record often experience reduced earnings and employment after prison, and housing insecurity and behavioral problems in children are hardships strongly related to fathers' incarceration, according to the report.

"When ex-inmates return to their communities, their lives often continue to be characterized by violence, joblessness, substance abuse, family breakdown, and neighborhood disadvantage," said committee vice chair Bruce Western, professor of sociology, Daniel and Florence Guggenheim Professor of Criminal Justice, and the director of the Malcolm Wiener Center for Social Policy at the Harvard Kennedy School of Government. "It can be challenging to draw strong causal conclusions from this research, but it's clear that incarceration is now a facet of the complex combination of negative conditions that characterize high-poverty communities in U.S. cities. Prisons are part of a poverty trap, with many paths leading in, but few leading out."

The report notes that deciding whether incarceration is justified requires an analysis of social costs versus benefits. This equation should weigh the importance of recognizing the harm experienced by crime victims, appropriately addressing those harms, and reinforcing society's disapproval of criminal behavior. However, the committee stressed that future policy decisions should not only be based on empirical evidence but also should follow these four guiding principles, which have been notably absent from recent policy debates on the proper use of prisons:

• Proportionality: Criminal offenses should be sentenced in proportion to their seriousness.

• Parsimony: The period of confinement should be sufficient but not greater than necessary to achieve the goals of sentencing policy.
• Citizenship: The conditions and consequences of imprisonment should not be so severe or lasting as to violate one's fundamental status as a member of society.
• Social justice: Prisons should be instruments of justice, and as such their collective effect should be to promote society's aspirations for a fair distribution of rights, resources, and opportunities.

The committee did not conduct an exhaustive review of literature on the effectiveness of alternatives to incarceration, crime prevention strategies, or victim assistance programs.

In a supplementary statement to the report, one committee member questioned some of the report's conclusions regarding the effect of incarceration rates on crime prevention and underlying causes of high incarceration rates. However, he concurred with the report's recommendations, which he noted are important and ripe for consideration by the public and policymakers.