"The biggest deterrent is for New Jersey law enforcement to track offenders down and prosecute," he said.

Already, the 1994 crime bill requires states to have such systems by next year to track offenders within their own borders.

It was not immediately clear how many juveniles were affected by the ruling, because the state attorney general's office does not track registered offenders by age.

It concluded that new restrictions would make it harder to track offenders and would "not enhance community safety."

After he sold his fleet of 32 trucks, he became a bail bondsman, and he tracked offenders who jumped bail to avoid trial.

Some entrepreneurs, who say the transmitters are stigmas - like electronic scarlet letters - have developed monitors to track offenders without attaching devices to their bodies.

To try to prevent similar crimes before they start, officers are using computer statistics to track chronic offenders and pinpoint hot spots.

Those with real information to post are likely to have enough to lose to be careful about what they do and it is relatively easy to track offenders down.

Professor Fiona Cameron is an academic psychologist who uses computer technology to help police forces track serial offenders.

FDLE offers Florida law enforcement agencies a geo-mapping system that tracks sexual offenders and predators within their jurisdictions.