Juvenile sex offenders must register on the state sex-offender registry if required by law, the South Carolina Supreme Court says.

The justices unanimously ruled Monday that forcing a boy to register after he was convicted of first-degree criminal sexual conduct when he was 9 years old does not violate the child's due process.

The S.C. Attorney General's Office says the registry is needed to protect the public against sexual predators.

Ronnie A -- as he was called in court papers -- pleaded guilty in August 2001 to first-degree criminal sexual conduct with a minor for having sexual relations with his 6-year-old sister when he was 9 years old, court papers said.

He was placed on two years probation.

In court papers, the state said the boy was expelled from school for inappropriate sexual behavior with a teacher, "touching little girls, and things of that nature."

The justices accepted the attorney general's argument that the boy's reputation would not be harmed because the names of children who committed offenses when they were younger than age 12 are kept off the public sex-offender list, as are the names of offenders between 12 and 16 who commit less serious offenses such as indecent exposure.

Those names are kept on a separate list available only to victims and witnesses in the cases, schools, day-care centers, and businesses and organizations that primarily serve children, women or vulnerable adults, according to SLED, which maintains the list.

More than 200 juvenile offenders are on the State Law Enforcement Division's list but are not named in the public registry.

The boy's lawyers had argued that forcing him to register as a sex offender for life violates his constitutional rights because it will remain on his record well into adulthood.

The problem with sex-offender registries is they typically exist long after offenders have served their sentences, said lawyer Denyse Williams, executive director of the American Civil Liberties Union of South Carolina.

"It runs into cruel and unusual punishment," said Williams before the case was heard this summer.

The ACLU is fighting sex-offender-registry laws in two cases before the U.S. Supreme Court, she said.

Karen Fryar, chief Family Court solicitor for Richland and Kershaw counties, said the public has a right to know about juveniles who have committed serious sexual offenses.

"If my kid is playing outside, and I suspect this other kid, I should be able to look it up," she said before the court heard the case in June.