Raising the age of when a young person automatically enters the adult criminal justice realm to 18 could save taxpayers millions and is a better way to treat youths sometimes prone to impulsive mistakes, a recent legislative study found.

Louisiana, where the official age of adulthood for criminal infractions starts at 17, is one of nine states that place the threshold so young. In recent years, several other states have moved to bump the age up to 18, often citing a growing consensus that teenagers are biologically different from adults — particularly in terms of their brain development — and should be treated differently.

The study, conducted by the LSU Health New Orleans’ Institute for Public Health and Justice, was ordered by a legislative resolution last year. Since the paper was released earlier this month, at least one lawmaker has come forward to say she will file a bill to move 17-year-olds to the juvenile court system.

The report examined four states that recently raised the age of juvenile jurisdiction to include 17-year-olds: Connecticut, Illinois, Massachusetts and Mississippi. In each of these states, lawmakers were swayed by evidence that teenagers’ brains are still developing and that for this reason, they “engage in more risky and impulsive behavior.”

“Having 17-year-olds automatically prosecuted in the adult system does not fit with any development science out there,” said Stephen Phillippi, director of the public health institute.

While the study says it could not complete a holistic cost-benefit analysis because of a lack of data, it predicted over the long run the state would see savings if 17-year-olds are kept out of the adult system. At first, there might be an initial cost to divert these teenagers to the juvenile system, and its programs geared toward rehabilitation, but the promise of keeping those offenders out of the adult system long term means savings, the report said. This is because studies show 17-year-olds treated as adults tend to recidivate, or commit more crimes, at higher rates than those dealt with in juvenile systems.

Phillippi said the state could expect major savings in just a few years, based off findings in North Carolina.

“If we follow the same basic algorithm, in five years we could probably expect, being conservative, anywhere from $15 to $20 million in savings,” he said.

Connecticut, which began the shift to include 16- and 17-year-olds in the juvenile justice system in 2007, now reports an annual $2 million in savings.

The study found that moving 17-year-olds to the juvenile justice system would not pose a public safety threat, noting that district attorneys would still have the power to move violent offenders, such as those accused of committing murder, rape or armed robbery, to the adult justice system.

“It’s important to note we’re not talking about egregious, heinous crimes,” Phillippi said. “The vast majority are nonviolent.”

The study found that the most frequent offenses that send 17-year-olds to adult jail include marijuana possession, simple burglary, simple battery, disturbing the peace. It also said that 17-year-old serious offenders are just as likely to change their criminal behavior as younger offenders who commit similar crimes.

“Every available data point points towards the conclusion that raising the age is doable, is safe and ultimately will save Louisiana money,” said Josh Perry, executive director of the Louisiana Center for Children’s Rights.

State Rep. Pat Smith, D-Baton Rouge, is drafting a bill to act on the report’s recommendation. “Even when they go into adult prison they’re separate from the adult population,” Smith said. “Raising the adult age to 18 is a logical move.”

But one key question ahead of the Legislature’s session in March is whether the Louisiana District Attorneys Association or Louisiana Sheriff’s Association will get behind the change, as their viewpoints are typically given a lot of weight by lawmakers. Representatives for both groups said they have not yet taken a position.

Experts say reforms during the past decade to make the juvenile system more developmental than custodial have put Louisiana in a better position to raise the age than in the past.

“We already know juvenile arrests are down,” Phillippi said. “We’ve been trending down for several years now. The arrest rate, the capacity from a detention standpoint and the utilization of detention facilities has trended down.”

While the report recommends the Legislature strongly consider raising the age of juvenile jurisdiction, the study also suggested one year of planning after legislation is passed to raise the age to 18. The study estimates that about 500 17-year-olds annually would go through juvenile court proceedings.

“In other states that have allowed a planning process, they transition fairly smoothly,” Phillippi said.

This study marks the first time Louisiana has formally reviewed the age of juvenile jurisdiction in more than 100 years. There is no preserved documentation explaining why the age of juvenile jurisdiction was set at 16 and then 17, the study says.

Four of the nine states, including Louisiana, that automatically try 17-year-olds as adults are actively trying to raise the age, the study said.

“I don’t think there’s any more study to be done,” Perry said.

Follow Danielle Maddox Kinchen on Twitter, @Dani_Maddox4.