TRENTON, N.J. -- Would you drive any differently if you knew there was a teenager behind the wheel of the car in front of you?

You might find out soon. A law in New Jersey will require new drivers ages 21 and younger to display identifying decals on their vehicles.

Gov. Jon Corzine signed the law Wednesday; it takes effect next year.

The decals will probably be a small reflective rectangle attached to the front and rear licence plates to help police enforce restrictions on probationary drivers, motor vehicle officials said.

Police will use them to determine whether teens are violating the state driving curfew and passenger restrictions, said Pam Fischer, director of the New Jersey Division of Highway Safety.

Authorities will not use the decals to target young drivers or pull them over for no reason, she said.

The decals are long overdue and will save lives, said Ron Gesualdo, owner of Gene's Driving School in Matawan.

"The parents are for it," he said.

"The kids don't say anything but you know what they're thinking."

One of those kids thinks the decals will only mean more trouble for teenagers.

"That's going to mean police are going to be bothering us even more," said Tebvon Mcneil, 18, of Paterson.

"They see that sticker on the car, they're just going to be pulling us over for no reason."

"Are there drugs in the car? That's the first thing they're going to think, because we're teenagers."

And not everyone thinks the new law will improve driver safety. Jennifer Collins, a 29-year-old Hamilton resident, wondered whether the stickers will distract other drivers who are looking for them in traffic.

"That really doesn't make any sense to me, honestly," she said.

Officials are considering using Velcro to attach the decals, so they can be removed by other drivers using the same car.

"It will probably be nondescript and simple and the public at large is probably not even going to notice it," Fischer said.

The decals were among a slew of new driving restrictions Corzine signed for young adults with probationary licences, which allow them drive unsupervised under certain conditions.

Other restrictions include changing the driving curfew to 11 p.m. from midnight; allowing only one other teenager in the car and banning the use of cellphones, even hand-free ones.

"These restrictions are in place because they represent the things we know put teens at risk," Fischer said.

New Jersey is the first state to require the decal, although Delaware and Connecticut have toyed with the idea, said David Weinstein, spokesman for AAA Mid-Atlantic.

The Delaware Department of Transportation is considering offering residents a reflective orange magnet that says, in black, capital letters: "NOVICE DRIVER." The magnets would be voluntary, said Dawn Hopkins, department spokeswoman.

The Insurance Institute for Highway Safety said 61 per cent of teenage passenger deaths in 2007 occurred in vehicles driven by another teenager. Twenty per cent of all passenger deaths occurred when a teenager was driving.

New Jersey's decal law was spurred by the driving death of a 16-year-old honour student in Morris County, Kyleigh D'Alessio, who was killed in 2006 riding in a car driven by a teenager with a probationary licence.

"No issue is more important than protecting our children, so these efforts are essential to that," Corzine said.

"We don't want to lose the beauty and the gifts that a Kyleigh could bring to all of us, and we need to take every step possible to make it something that doesn't occur in the future."