MONTPELIER, Vt. (AP) — Vermont is hoping to place fewer young adults in the adult criminal justice system using a first-in-the-nation law that will place some teenagers 18 and older in the juvenile justice system.

A law signed by former Democratic Gov. Peter Shumlin in 2016 took effect July 1 and allows anyone 21 or younger charged with a nonviolent crime to be eligible for juvenile offender status. In May, a bill was signed into law by current GOP Gov. Phil Scott that will begin placing those under the age of 19 in the juvenile justice system by 2020, and raise the age again to those under 20 in 2022.

In both cases, the change in procedure does not apply to a dozen violent offenses, including murder and armed robbery.

Lawmakers said increasing the age in the juvenile system may prevent young offenders from committing future crimes. A study from the United States Sentencing Commission found those under 21 have the highest rate of recidivism, but the hope is that by placing them in the juvenile system and placing a greater emphasis on rehabilitation, the criminal justice system can help them age out of criminal behavior.

"If they make a couple of mistakes, they'd be dealt with in the adult court, where failure is a likely outcome," said Sen. Dick Sears, a Democrat from Bennington County and sponsor of this year's bill. "Or, they could be dealt with in a combined juvenile and adult system where some success is more than likely possible in preventing further criminal activity."

Lael Chester, director of the Emerging Adult Project at Columbia University's Justice Lab, said reevaluation of how the criminal justice system deals with young adult offenders is motivated by research in the past decade that shows the brain is not typically fully developed until the mid-20s.

"The 18th birthday is not magical; you do not suddenly become a fully fledged adult," said Chester.

While 18 is the age of majority in Vermont and most other states, Chester said current law recognizes people under 21 should not buy alcohol, and car rental companies generally require customers to be 25.

Massachusetts, Connecticut and Illinois have also considered legislation that would raise the age in the juvenile justice system. On a smaller scale, jurisdictions across the country have experimented with programs that treat young adult offenders differently than their older counterparts.

On a trip to Germany, Connecticut Correction Commissioner Scott Semple saw how the criminal justice system there dealt with young offenders differently and decided to implement a program in his state.

In a repurposed house unit at Cheshire Correctional Institute in Connecticut, staff members who are trained in neuroscience development work with men ages 18 to 25. The program, which launched a year and a half ago, has not been around long enough to determine how the program affects recidivism, but the dramatic drop in violence and other incidents has them planning to expand, Semple said.

"It's worked so well that we're expanding it here in Connecticut," Semple said. "We'll be opening a second unit specifically identified for women, and then we hope to potentially expand the adult unit."

Chester said the idea is novel, but preliminary research and anecdotal evidence show promising results, and she hopes more states follow Vermont's lead.