Correctional Service Canada is violating the rights of Indigenous inmates by using culturally biased tests that keep them behind bars longer and in more restrictive environments, the Supreme Court of Canada heard today in a case that could have sweeping ramifications for the federal prison system.

The high court heard arguments in the case of Jeffrey Ewert, a Métis inmate who claims the tests that determine prison security level and parole decisions discriminate against Indigenous offenders.

He is serving a life sentence for second-degree murder and attempted murder, and has been in the federal system for 30 years in prisons across the country.

Ewert's lawyer Jason Gratl argued that while the tests are statistically valid and legitimate for the general population, they do not take into account the significant linguistic and cultural differences of Indigenous inmates. He said Correctional Service Canada (CSC) failed for decades to ensure the integrity of its assessment process and has therefore breached fundamental justice.

Gratl said CSC must take "all reasonable steps to ensure that any information about offenders that it uses is as accurate, up to date and complete as possible."

Federal government lawyer Anne Turley said standard assessments are used around the world, including in prison populations with Indigenous offenders in the U.S., Australia and New Zealand. They have proven to be "reliable predictors" of risk, she said.

Professional psychologists take a number of steps in a "multi-faceted approach," including an in-depth interview, in addition to the tests that are now under scrutiny.

"They are not the only tool in the tool box," Turley said.

No 'causal connection'

Suggesting the trial judge erred in finding a "causal connection" between the use of the tool and the loss of liberty, Turley said in Ewert's case, decisions on security classification were based also on clinical assessment, discussions with parole officers and a review of behavioural pattens and treatment plans.

Justice Malcolm Rowe said he is "quite sympathetic to the fact that there is a serious problem here," but suggested Gratl was using a constitutional argument to force federal action without laying out a clear argument.

"If I were a member of Parliament or a senator, and this was evidence which was being presented to me as I was studying Corrections Canada, I would be deeply concerned and I would probably be motivated to call upon the government to review these matters. But I'm not a parliamentarian, I'm a jurist, and you've asking us to invoke the Constitution so as to enjoin the federal government to take a course of action."

Data provided to CBC News by correctional investigator Ivan Zinger's office shows that Indigenous offenders are less likely to get parole than non-Indigenous inmates and spend longer portions of their sentence behind bars.

It also shows that the percentage of Indigenous offenders has reached a record high of 27.4 per cent of the total inmate population, according to most recent statistics from August 2017.

Since 2012, the Indigenous inmate population increased by 21.3 per cent, while the non-Indigenous inmate population declined by 11.8 per cent.

Female Indigenous offenders make up 37.9 per cent of the total female inmate population. Of the overall female Canadian population, Indigenous women and girls comprise just four per cent, according to Statistics Canada. (Ueslei Marcelino/Reuters)

Female Indigenous offenders now make up 37.9 per cent of the total female inmate population. Of the overall female Canadian population, Indigenous women and girls comprise just four per cent, according to the most recent census data from Statistics Canada, dated 2011.

Indigenous people make up 4.3 per cent of Canada's total population.

Paul Champ, representing the B.C. Civil Liberties Association and the Union of British Columbia Indian Chiefs, said the burden of proving the reliability and validity of tests rests with the state. It must also be considered in its historical context.

Consider cultural values

"For our criminal justice system to operate fairly, decision makers must take into account the special circumstances and different cultural values of aboriginal peoples," he said.

Independent Senator Kim Pate, a long-time prisoner human rights advocate, noted it is difficult for a prisoner's case to make it to the country's highest court, and said a favourable decision for Ewert could force CSC to address "systemic inequalities" in the assessment and classification process and develop more nuanced techniques.

"These are brilliant jurists and I am therefore hopeful that the court will recognize and decide to remedy the longstanding and growing inequalities experienced by prisoners, especially those who are marginalized by race, sex and disability," she told CBC News.