The scale of long-term solitary confinement in Canada is unknown because of disparities in data among the country's 14 prison services – a major oversight in record keeping that threatens to derail policy makers who have vowed to reform the practice in the face of harsh global criticism.

While the federal Correctional Service Canada maintains precise data on federal inmates – those serving sentences of two or more years – the provincial and territorial systems keep wildly uneven stats on segregated inmates, a Globe and Mail analysis has found.

Last September, The Globe asked all 13 provincial and territorial prison systems in the country for aggregate numbers of inmates who spent more than 15 days in segregation for each of the past five years. The United Nations Special Rapporteur on torture has identified 15 days as an important threshold, beyond which inmates can suffer permanent physical and psychological harm.

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Given six months to come up with a response to the request, Alberta said, "We're still looking into the stats." New Brunswick had a similar answer.

Only Quebec was able to fully comply with the request.

Ontario, Manitoba, Newfoundland and Prince Edward Island could all provide precise counts for the number of segregated inmates on a given day, but could not furnish long-term figures.

A spokesman for the Ontario Ministry of Community Safety and Correctional Services advised that such a search would require public servants to "manually go through hundreds of thousands of paper files to ensure accuracy."

The remaining jurisdictions also could not provide long-term data.

These major holes in prison data have thwarted efforts by academics and journalists to create an accurate snapshot of long-term solitary confinement, a correctional method recently condemned by U.S. President Barack Obama, the UN Committee Against Torture and Pope Francis.

"We know that people die in segregation, we know that people come out significantly harmed by segregation, and yet we don't have any basic accountability or transparency about the practice," said Debra Parkes, associate dean in the University of Manitoba Faculty of Law. "I think that's a problem in a society committed to the rule of law."

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In Quebec's case, within days of The Globe request, a Ministry of Justice spokeswoman sent a detailed table showing that, in the past five years, 16 inmates have spent more than 15 days in isolation. None of those 16 cases lasted in excess of 35 days, according to the chart. The Quebec figures are low considering the entire federal prison system houses barely 50 per cent more inmates than Quebec and yet registered 407 segregation admissions of more than 30 days in 2013-14.

The Yukon Territory was also able to provide a good deal of information. Since 2014, the territorial Department of Justice has published detailed figures on solitary placements on the government website. So far, none have exceeded 15 days, according to the website.

Ms. Parkes encountered these shortfalls in prison data first-hand when she requested 2010 segregation records for two Manitoba institutions: the women-only Portage Correctional Centre and Headingley Correctional Centre. The province initially denied her request, saying no such records existed in any collated form, but then acknowledged that the information was available if a researcher scoured each inmate's file for the entire year.

Ms. Parkes compelled the laborious search through an Access to Information request. She got back hundreds of pages documenting segregation placements at Portage and a bill for $5,000.

The provinces and territories lack another key accountability measure present in the federal system: an independent prison ombudsman. The federal Office of the Correctional Investigator has fielded inmate complaints for 43 years and has open access to the Correctional Service Canada Reporting System. Its reports are crammed with data of every kind. Provincial and territorial systems, by contrast, only answer to occasional probes by provincial ombudspersons who have far broader mandates.

"Legally speaking, the importance of data is that certain kinds of claims are impossible to make without it," said Lisa Kerr, assistant professor of law at Queen's University. "You cannot show a violation of s. 15 of the Charter [guaranteeing equality rights] without showing, for example, that most of the inmates in segregation are aboriginal."

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Ms. Parkes was not deterred by her Manitoba experience. She recently requested solitary-confinement records for youth imprisoned in all the provinces and territories. A hodgepodge of responses came back. "It was very uneven," she said. "It ranges from jurisdictions where they say they have no records at all, to jurisdictions that gave me everything."

The process is laborious, but necessary, she says.

"Everybody's concerned about solitary confinement, as they should be," she said. "But I think to address solitary confinement, we need to be looking more broadly at huge gaps in accountability with respect to corrections. We first need the information and only then can we figure out how to change things."