At least four inmates at Auckland Women's Prison were gassed with multiple canisters of pepper spray while inside their cells in an approved tactic their lawyer says is risking lives.
Two of the prisoners spent four months in a segregation unit where they had to lie face down on the ground, often with their heads beside the toilet, if they wanted to be fed.
They sometimes went days without food if they refused to comply with what they saw as a humiliating ritual.
One of the inmates became severely depressed and attempted suicide but was resuscitated and returned to the segregation unit the next day, in conditions likened to being kept like caged animals.
The treatment has come to light after three inmates were charged with burning prison property and the court case over the arson revealed the conditions the women faced at New Zealand's largest women's prison.
Investigative Journalist Guyon Espiner reports.