TORONTO - Ontario's highest court dismissed a thorny constitutional challenge to the province's sex offender registry Friday, ruling that the public's right to safety trumps any potential infringements on an offender's freedoms.

While the registry does violate an offender's liberties to a modest extent, sex criminals are "prolific" and "likely to reoffend," said Appeal Court Justice Robert Blair.

"There is no way to know in advance which sex offenders will reoffend and which will not, and that is why all are included on the registry," Blair said in his 39-page judgment.

He added that the registry gives police a valuable investigative tool when a sex offence occurs, and appearing on the list doesn't impede a person from "doing anything or going anywhere."

The legal wrangling, which was kick-started by convicted offender Abram Dyck in 2002, worked its way through two lower courts before arriving at the Appeal Court last November.

Among other issues, the polemic centred on the contention that the registry constituted "cruel and unusual punishment" and violated Dyck's charter rights.

During arguments last year, Dyck's lawyer Stephen Gehl told court the current law casts too wide a net and puts someone convicted of a minor assault - like touching a woman's bottom - in the same category as a dangerous pedophile.

Gehl argued that the law's broad nature snares people who are unlikely to offend and intrudes on their liberties.

Known as Christopher's Law, Ontario's registry was created on April 23, 2001 - one day after Dyck was released from jail after serving an 11-month sentence for sexual interference.

But one critic said there's little evidence that offender registries help decrease the number of sex crimes.

"The criminal justice system is a blunt instrument," said Craig Jones, executive director of the John Howard Society of Canada, an advocacy group for people with criminal records.

Along with increasing media attention about sex assaults, offender lists simply frighten the community, Jones said.

Increased community awareness can also often lead to increased stress for offenders who have already served their time.

"They're hounded from town to town, from address to address," Jones said of listed offenders.

"And the longer that goes on, the greater the stress, and the more likely they are to reoffend."

As of November, Ontario's registry, which was the first of its kind in Canada, listed 7,909 offenders.

Police say the registry - which contains the offender's name, date of birth, address, photo and details of the crime - is an invaluable tool in tracking repeat sex offenders.

Christopher's Law forces offenders to sign up when their sentence is finished and to check in annually for 10 years. For repeat sex criminals, and those who served more than 10 years in jail, the reporting period continues for life.

Friday's ruling follows new Ontario government amendments that now force sex offenders living in the community to be added to the registry.

Before those amendments, brought into law on Wednesday, offenders were forced to sign up only when they were released from jail, or if they were convicted without a custodial sentence.

In 1988, a paroled pedophile named Joseph Fredericks told police in Brampton, Ont., that he had kidnapped, assaulted and killed 11-year-old Christopher Stephenson, who became the law's namesake.

In 2004, the federal government brought in a national registry, but it has faced heavy criticism because it places too much power in the hands of local police forces and is hampered by privacy restrictions.