Officer Geoffrey Napper, right, and Officer Nick Cook patrol Woodland Terrace, a public housing complex in Southeast Washington, in July 2015 after a spate of slayings in the neighborhood. (Evelyn Hockstein/For The Washington Post)

The law students came armed with charts and statistics about arrests, crime trends and recidivism rates. More important, they came with budget numbers — trying to show how reducing the number of people arrested and put behind bars can save the District money.

And, the students said, that money should be given right back to the criminal justice system to continue reforms that help more people stay out of trouble, or at least not repeat past mistakes.

“Why not the Justice Reinvestment Initiative?” Melvin Scott, a senior at the University of the District of Columbia, said at a forum Tuesday night that included the District’s city council chair and deputy mayor for public safety.

Scott’s quote became a mantra for four other students as they presented their ideas to reform the District’s criminal justice system, notably by incorporating the Justice Reinvestment Initiative, a program being used by 27 states, including Maryland, and developed by the Bureau of Justice Assistance, part of the U.S. Department of Justice. The forum was led by their professor, Edwina Dorch.

The Justice Reinvestment Initiative helps states fund data studies of arrests and other factors that drive incarceration rates, and look at efforts such as diversion programs to keep nonviolent offenders out of prisons. Then it determines how much money can be saved. The government then matches that amount in grants back to the states.

The District does not use the program, and officials who were at Tuesday’s event did not address whether participation would be sought. Many used their time to showcase existing programs used to help offenders either stay out of prison or get help re-entering society after getting freed.

Scott showed D.C. police figures showing that the number of arrests dropped from about 51,000 to 41,000 from 2011 to 2014. If that trend continues, Scott said, the District could reap $7 million in savings.

Other students pointed to drops in the population at the D.C. jail and with the number of people on supervised release. All meant cost savings, they argued, that could be put back into programs to help those in trouble with the law. Ronald Mason, president of UDC, told students that the criminal justice system has been less about achieving justice and “more about a system of law and order.”

Kevin Donahue, the District’s deputy mayor for criminal justice, noted that many crimes, including homicide, have dropped sharply since the late 1980s but plateaued in recent years.

The deputy mayor said that the District could take full control of the D.C. jail. The medium-security Correctional Treatment Facility, next to the general detention center, is run by a private company whose lease expires next year.

Donahue said that the District can run the center more efficiently — an initial $5.9 million investment, he said, could save the District $5 million in years to come and allow for the hiring of 200 additional people. More important, he said, it would give the city room to offer more mental health treatment and space to offer training to prisoners.

Donahue stressed that the cause of crime is complex, rooted in myriad social ills and challenges, including poverty, mental health, living amid violence, broken homes, and drug and alcohol abuse. He said District officials are beginning to harness efforts to address such problems, and are bringing neighborhood stabilization units into areas hit by homicides and shootings.

Donahue came up with the idea for the stabilization unit one day last winter, during what promised to be a mild snowstorm. While discussing the District’s response to the storm with about two dozen other city leaders, he got a text message about a shooting. He thought, “If only I had the same focus on the shooting as we had on the snowstorm.”