Last week, a 17-year-old who got into a fight or was caught stealing faced serious jail time if convicted.

That is no longer the case, effective today.

Under a new state law, teenagers convicted of non-felony offenses will be provided with a range of community-based treatments, rather than automatically being sent to the adult court system and its harsher penalties.

In passing the law, Connecticut joins 38 other states in setting the age of an adult for less-severe offenses at age 18, according to the Campaign for Youth Justice.

“This is the best thing our state has done in decades,” Department of Correction Commissioner Leo Arnone told a panel at the state Capitol complex last week.

The change in the law means 4,000 cases involving 17-year-olds will now be handled by the juvenile court system each year. By Arnone’s count, about 160 fewer 17-year-olds will be sent to adult prisons every year.

Teens charged with murder, rape, homicide, aggravated assault and robbery — the most serious felonies — will still be treated as adults. Some felonies, such as carrying a firearm, will be up to a judge’s whether it’s tried in an adult of juvenile court.

“Juveniles will be diverted into more effective treatment. There will be less crime. There will be fewer juveniles in detention,” said Michael Lawlor, the governor’s criminal justice adviser. He said he also suspects it will help chip away at the state’s disproportionate incarceration of black and Hispanic children.

A study commissioned by the state before this bill became law found that up to 75 percent of teenagers sent to the adult system were receiving no rehabilitative services. And the services some teens did receive were subpar, according to the study.

Two years ago, the state began treating 16-year-olds who had committed everything but the most serious felony offenses as juveniles, and Lawlor pointed to the success of this change in arguing for raising the adult age still one more year. Among other positive results involving the 16-year-olds, the Connecticut Judicial Branch reported a drop from 51 percent to 45 percent in recidivism rates since 2007.

Judge Barbara Quinn, the chief court administrator, attributed this success to all the alternative services the state budget has provided for rehabilitation.

“What’s available today is just absolutely incredible,” she said.

When the earlier law was passed, there had been concerns about cost and about it overburdening the juvenile system. The state’s nonpartisan Office of Fiscal Analysis, in fact, had estimated the shift would cost the state $100 million a year.

But Judicial Branch officials said these concerns have been alleviated because court referrals remain at historic lows. In the most recent two-year state budget, $17 million was allocated to pull 17-year-olds under the juvenile umbrella.

“Community placements are far, far less expensive,” said William Carbone, executive director of the Judicial Branch’s court support division.

Even the state’s attorney office approves.

“This change has been good. I think it surprised us,” said Kevin Kane, the state’s chief prosecutor, of the continued drop in referrals.

Wait times for community-based treatment and mental health placements have also not been affected, according to the Judicial Branch.

While state officials are optimistic the new law will be similarly successful, Lawlor said he will be watching closely. “Only time will tell.”

Want to hear more? Listen to WNPR’s “Where We Live” broadcast about 17-year-olds being treated as children by the courts here.