A Montreal woman is suing Correctional Service Canada, claiming she was kept in solitary confinement too long.

Quebec Superior Court Justice Chantal Masse authorized a class-action lawsuit earlier this month. The suit contends the agency puts too many prisoners in isolation and keeps them there too long.

The plaintiff, Arlene Gallone, spent nine months in the Joliette Institution for Women for her part in a robbery. She says during that time, she spent two three-month stretches in solitary confinement.

"I felt like an animal," she said. "You do not lock a dog in cage for three months."

Gallone has been out of prison for two years.

Seeks $10K per person

The lawsuit is demanding $10,000 in compensation for anyone who has spent more than 72 hours in isolation in the past three years.

The United Nations says any longer than 15 days in solitary confinement could amount to torture, and it wants countries to ban the practice.

Clara Poissant-Lespérance, Gallone's lawyer, says the practice contravenes the Canadian Charter of Rights and Freedoms, citing studies that show solitary confinement can lead to lasting mental health problems.

According to Howard Sapers, the former correctional investigator of Canada, about 8,300 inmates spent time in solitary confinement in 2014-2015.

Last month, a judge in Ontario certified a class-action lawsuit against Correctional Service Canada alleging Canada didn't provide adequate medical care to mentally ill inmates and unduly subjected them to solitary confinement.

with files from Radio-Canada's Émilie Dubreuil and CBC's Jay Turnbull