The federal prison system is growing at an unsustainable rate, according to a new study from the Urban Institute’s Justice Policy Center, which reports that the federal inmate population has ballooned by almost ten times since 1980.

There are about 218,000 inmates in federal prisons, according to the report. More than half of the population consists of drug offenders. The study’s authors attribute the length of sentences — particularly for drug offenders — as an important driver of population growth.

The report calls for policymakers to study state justice systems that have demonstrated the ability to cut prison spending without jeopardizing public safety.

“Reducing sentence length, particularly for drug offenders, would be the most direct way to slow the projected growth of the BOP population,” suggest study authors, who note that lawmakers are responsible for sentencing guidelines.

Read the report HERE.