Solitary goes by many names: restrictive housing, administrative segregation, the SHU or the hole. People can be placed there for violent acts, but also for minor rule violations, for their own "protection" or while under investigation. Some stay for years or decades.
A 2023 report by Solitary Watch and the Unlock the Box campaign found at least 122,840 people held in solitary on a given day in US prisons and jails. Research links isolation to anxiety, psychosis, self-harm and higher suicide risk. Black people are overrepresented in solitary, as are people with mental illness.
The UN's Nelson Mandela Rules, adopted in 2015, ban solitary beyond 15 consecutive days. Some states have passed limits, including New York's HALT Solitary Confinement Act, which caps most stays at 15 days. Enforcement of these limits has been uneven.