Peel police officers discriminated against a six-year-old black girl when they handcuffed her wrists behind her back and kept her restrained for nearly half an hour at a Mississauga, Ont., school, Ontario's Human Rights Tribunal says.

In a decision issued late last month, the tribunal ruled that race was a factor in the Sept. 30, 2016 incident. That morning, two white Peel Regional Police constables attended the public school after administrators requested assistance with the girl, who they said was acting violently.

CBC Toronto is not identifying the family or the school to protect the girl's identity.

During their interaction with the young girl, the 54-page decision reads, the officers placed her on her stomach and cuffed her at the wrists and ankles. She was then kept in that position for 28 minutes until paramedics arrived.

Adjudicator Brenda Bowlby called the response a "clear overreaction" that can only be explained, at least in part, by the officers' implicit racial bias.

The girl and her family asked the tribunal to hear their case against the Peel police services board in September 2017 and hearings were held over seven days last year. The family is also pursuing a civil lawsuit against Peel police.

Speaking to CBC Toronto in February 2017, the girl's mother said there was "no excuse" for how the officers handled the incident.

"My daughter didn't have a knife, my daughter didn't have a gun, there's no way my daughter could've harmed anybody in that situation," she said.

"There's nothing a 48-pound, six-year-old girl could've done."

Officers denied key elements of incident

During the hearings, the officers said that they repeatedly tried to verbally de-escalate the situation before the girl was restrained.

In her decision, Bowlby wrote that the girl was "spitting, head-butting and trying to break free" as they attempted to restrain her without cuffs.

"She began kicking the officers, swinging her legs out sideways and coming backwards like a heel kick," Bowlby added.

The call to police from administrators on Sept. 30 was the fourth about the girl that month. Before the constables arrived that particular day, she had hit a student, tried to hit another, thrown objects at the principal and struck her behavioural teaching assistant in the face with a book, school staff said.

Before police arrived, the behavioural teaching assistant — trained in child crisis prevention and intervention — tried to physically restrain the girl using a technique called a "child lock hold," but he was unable to calm her.

During the hearings, both officers denied placing the girl on her stomach at any point in the 90 minutes they were at the school. That testimony, however, was contradicted by the teaching assistant, whose account Bowlby found to be the most reliable.

The tribunal also heard from two expert witnesses who testified about implicit bias in policing.

Actions were 'disproportionate'

Ultimately, Bowlby found that although the officers "conducted themselves throughout the incident in a professional and polite manner," their actions were "disproportionate to what was necessary."

"While the officers had a legitimate duty to maintain the safety of the [girl], others and themselves in circumstances where the [girl's] behaviours were challenging and might have created a safety risk, this did not give them licence to treat the [girl] in a way that they would not have treated a white six-year-old child in the same circumstances."

In a statement, Peel Regional Police noted that both officers were investigated by the Office of the Independent Police Review Director and no formal charges were laid.

"However it was determined as a result of that investigation, that these officers, and all officers responding to schools, would benefit from further training, which is being implemented," the statement continued.

The tribunal's ruling does not outline any possible remedies, but another hearing will be held to decide what happens next.