Locking up juveniles before trial may make them more likely to commit crimes afterward, according to a new report by the Justice Policy Institute, a Washington-based think tank that seeks alternatives to incarceration.

Young people in a San Francisco program to keep young people out of detention are half as likely to commit later crimes than those who stay in detention or the juvenile justice system, said the report by by Barry Holman and Jason Ziedenberg.

"Detention centers do serve a role by temporarily supervising the most at-risk youth," they wrote. "However, with 70 percent being held for nonviolent offenses, it is not clear whether the mass detention of youth is necessary -- or being borne equally."

Overall, they wrote, about 500,000 juveniles are held before trial each year. A study for the Wisconsin Legislature looked at four counties and found that 70 percent of the juveniles held before trial were arrested again within a year.

The 20-page "policy brief" was being released Tuesday, as part of a conference for the 75 court systems, including New Orleans, working with the Annie E. Casey Foundation's Juvenile Detention Alternatives Initiative.

A news release from the institute said New Orleans was chosen for the conference because of its success in changing the juvenile crime system after Hurricane Katrina hit Aug. 29, 2005.

Both juvenile arrests and pretrial incarceration have dropped dramatically, said New Orleans Juvenile Court Chief Judge David Bell, who was elected one of the city's six juvenile court judges eight months before the hurricane.

In the eight months prior to Hurricane Katrina, there were approximately 5,700 juvenile arrests. "And on any given day, there were a minimum of 108 kids in detetention," Bell said.

So far this year, he said, slightly more than 300 juveniles have been arrested, and the detention facility has held about 13 people a day.

"That's not 13 new arrests, but 13 kids a day," he said.

And, he said, the city's 147 murders this year have not been fueled by juvenile crime. "Post-Katrina, we have yet to have one child in Orleans Parish arrested for murder," he said, adding that there was one juvenile arrested for attempted murder.

Sgt. Jeffrey Johnson, a New Orleans Police Department spokesman, said that before the storm detention was automatic for arrested juveniles.

Now, he said, police call a detention judge who decides whether to hold the child. The following morning, the district attorney decides whether to release them or take them to a judge at noon.

New Orleans' juvenile courts have just received a grant to create a center where juveniles will be assessed for danger to themselves and the community almost as soon as they are arrested, Bell said. Plans are for police to call the center, which would decide whether the juvenile should be released directly to his or her parents, be fitted with an electronic monitor, or be held, he said.

(Copyright 2006 by The Associated Press. All Rights Reserved.)