B.C. children's watchdog says a controversial penile testing used on young sexual offenders must never be reinstated by the provincial government.

In a report released today, Mary Ellen Turpel-Lafond said there is no way to know if the penile plethysmography tests, or "phallometry," actually works to assess and treat young offenders.

The "Peter Meter" tests require boys as young as 13 in sex offence treatment programs to measure their sexual arousal level and help treat their dangerous behaviour.

The boys view pictures of nude and semi-clad children and listen to audio descriptions of forced sexual scenarios while a ring device is attached to their penis.

A review of the 25-year-old program was ordered after authorities learned one of the male technicians administering the tests was charged with sexual assault in an unrelated case.

The testing was also called into question by the BC Civil Liberties Association and the group Justice for Girls.

Supporters of the testing, which is still used on adults, insist that it is justified as a tool to rehabilitate sexual offenders while they are still young – arguing it could prevent future sex crimes.

But others believe that the deeply personal and intrusiveness of the penis testing could be potentially compounded, especially if the youth may have been sexually victimized themselves.

Turpel-Lafond says there hasn't been enough research on using the test in young people to justify using it in B.C.

"With a procedure so invasive, so controversial by its very nature and so questionable in its reliability, great care must be exercised when dealing with a young and often vulnerable population," she wrote.

"The greatest of care with what is known at this time means not using PPG testing on youth in British Columbia."

A veteran forensic psychiatrist who worked on the Kimberly Proctor murder case says the province has taken away a valuable tool that could prevent young offenders from becoming sexual offenders as adults.

Dr. Roy O'Shaughnessy says the test is important because it helps therapists detect whether young people have deviant sexual arousal.

He also believes it's better to have that information at a young age, to bolster the chances of rehabilitation.

"For many, we can teach them how to control arousal and change their lives," he said.

"It may prevent them from becoming adult sexual offenders."