HALIFAX -- The disturbing case of a 16-year-old Halifax girl who was lured into the sex trade and abused by a 40-year-old woman drew to a close Thursday as Renee Allison Webber -- a single mother with four children -- was sentenced to four years in prison.

At a time when the girl should have been settling in to high school, she was instead drawn into prostitution by Webber and her partner in crime, said Justice Christa Brothers.

"She was involved in an insidious underworld, where she was exploited, abused and commodified -- and eventually used for Ms. Webber's own sexual gratification," Brothers said in Nova Scotia Supreme Court.

In September, a jury found Webber guilty of trafficking a person under the age of 18, sexual exploitation, advertising sexual services, assault and receiving material benefit from trafficking.

Brothers said the girl, whose identity is protected by a publication ban, left her mother's home to stay with friends in late 2015, and later moved in with Webber to escape a "tumultuous" life.

The girl was told she would work in the sex trade as part of a team, receiving protection from a man named Kyle Leslie Pellow -- who was himself jailed in the case.

The crimes were committed over a four- to six-week period, the judge said.

Brothers said she accepted as fact allegations that Webber slapped the girl at one point, and also engaged in sexually inappropriate behaviour with her.

However, Brothers said Webber did not use violence to keep her in the sex trade.

"The complainant was a vulnerable young person when Ms. Webber met her," the judge said. "She was vulnerable and exploited, and this cries out for denunciation and deterrence."

Brothers cited a 2018 court ruling from Ontario, which summarized the "evils and realities" of human trafficking.

"At its most basic level, it is a form of slavery, with pimps living parasitically off the earnings of prostitutes," she said.

The judge said the victim's age was an aggravating factor, but Brothers also noted that Webber, now 43, was a first-time offender with a supportive family.

Outside court, the girl's mother said the sentence was too light.

"A stronger message should have been put forward," she said, adding that her daughter is doing well.

"She's brave. She came forward ... And when she did, she did so out of fear. She knew that if she didn't come forward, they would come back or continue doing the crime to other girls."

Though the human trafficking charge normally carries a mandatory minimum sentence of five years in prison, Brothers agreed with the defence's argument that mandatory minimums violate the section of the Charter of Rights and Freedoms that says Canadians have the right to be protected from cruel and unusual punishment.

Her decision mirrors similar rulings handed down in Ontario and British Columbia, said defence lawyer Don Murray.

Crown lawyer Cory Roberts had asked for a six-year sentence.

"Nonetheless, it sends a strong message both to Miss Webber and other who may consider trafficking young girls," he said.

"Human trafficking is akin to human slavery. You're talking about controlling the movements for the purpose of exploiting them."

Webber's co-accused, Kyle Leslie Pellow, pleaded guilty last June to trafficking a person under 18, advertising sexual services and breaching a court order.

He received a six-year prison sentence, but the judge deducted just over three years for time served.