NEW YORK - US federal prosecutors moved Thursday to sue New York over rampant mistreatment of 16-to-18-year-old detainees at the city's notorious Rikers Island prison.
The Department of Justice on Thursday sought court permission to join a civil lawsuit which accuses New York's Department of Correction of using excessive force against the youngest inmates.
The intervention follows a two-and-a-half-year investigation which Manhattan attorney Preet Bharara said uncovered "a pervasive and deep-seated culture of violence" at the jail in the East River.
Rikers Island is one of the largest municipal jails in the United States with an average daily population of 14,000. Most of the inmates are in pre-trial detention.
An investigation found that staff frequently punch, strike or kick young inmates in the head and face, and that fighting between inmates is common.
The violence triggered a staggering number of injuries. For example, in 2013, there were 565 incidents of force against an average of 683 underaged detainees.
New York one of only two states in the US that automatically charges all those aged 16 and over as adults.
US Attorney General Eric Holder said he was taking legal action to ensure that vital reforms, recommended in a report in August, were implemented swiftly.
Holder said there was "alarming evidence" of excessive use of force against juveniles, and a systemic failure to protect them from violence and solitary confinement.
"This action allows the justice department to seek necessary reforms to remedy these unlawful conditions," Holder said.
The youngest inmates are subject to "rampant use of unnecessary and excessive force" inflicted by prison staff and other inmates, prosecutors said.
"This violence is the result of widespread and longstanding systemic deficiencies within DOC and its jail complex on Rikers," said Bharara in court papers filed on Thursday.
The August report urged the city to implement over 70 reforms and although prosecutors said the department's new leadership had taken some positive steps, they said much more needs to be done.
The average daily adolescent population at Rikers has fallen from 791 in 2012 to 489 in 2014.
In 2013, around 50 per cent of the adolescents were diagnosed with some form of mental illness.