He documented the cruelties of white South African rule, and he was made to pay for it, enduring beatings and 586 consecutive days in solitary confinement.
Prolonged periods of being locked up alone can cause heart disease and mental health problems, experts say. Backers say the practice keeps guards safe.
The City Council vote has highlighted a broader debate over whether solitary confinement is torture or a legitimate form of punishment for violent detainees.
The New York City Council is expected to approve a bill to ban solitary confinement this week over the objections of Mayor Eric Adams, who may veto it.