NEW YORK (AP) — New York agreed on Wednesday to overhaul how thousands of state inmates are punished within prison walls, settling a long-standing lawsuit by accepting a range of reforms to how solitary confinement operates.

The agreement, filed in federal court in Manhattan, comes after years of negotiations with the New York Civil Liberties Union, which sued the state over 23-hour confinement for rule violations, arguing the practice was extraordinarily harsh and psychologically damaging.

"Massive culture change is a challenge," Donna Liberman, the executive director of the NYCLU, told reporters in announcing the agreement. "We need to be monitoring like a hawk and we will be monitoring like a hawk to ensure that the reforms are actually carried out. "

Once approved by a judge, some of the reforms outlined in the $62 million, five-year plan should be implemented within three months.

Those include moving 1,100 of the roughly 4,000 prisoners currently serving time in solitary confinement for minor or nonviolent offenses into more secure, therapeutic housing units.

There are almost 60,000 prisoners in New York, housed in 54 prisons throughout the state.

The agreement also requires the state to retrain its 20,000 prison guards on de-escalation and other techniques, caps the number of days to 30 a prisoner will serve for a first-time, nonviolent offense, reduces the number of violations that carry solitary sentences and for the first time imposes a three-month maximum sentence for most rule violations.

The agreement leaves open exceptions for prisoners who commit extreme acts of violence or escape but also provides so-called step-down programs to effectively acclimate prisoners who have been in long-term isolation, even for violent offenses, before they're released from custody.

After the NYCLU filed its lawsuit in 2011, Gov. Andrew Cuomo saw it as an opportunity to improve New York's prison standards and instructed his staff to negotiate, said Alphonso David, the governor's top lawyer

"This agreement will not only decrease the number of people who will enter solitary confinement but it will also create a safer environment" for prison guards and the community, David said.

The use of solitary confinement as a tool to punish inmates who break prison rules has come under increased scrutiny throughout the country in recent years.

Corrections officials in Colorado, Mississippi and Washington have already taken steps to severely reduce their reliance on long-term isolation. Last year, a state advisory committee to the U.S. Commission on Civil Rights recommended the practice be eliminated for young inmates, citing growing evidence that the practice is emotionally and mentally harmful.

But the success of the proposed reforms in New York will likely depend on the cooperation of the powerful union representing prison guards, which was not a direct party to the negotiations, and has long argued that solitary is necessary to control prison blocks.

New York State Correctional Officers & Police Benevolent Association President Michael Powers said in a statement that while his union was still reviewing the settlement, "it is simply wrong to unilaterally take the tools away from law enforcement officers who face dangerous situations on a daily basis."

Tonja Fenton, one of the plaintiffs in the NYCLU lawsuit, served 270 days in solitary for three minor offenses, including one for mailing a sample of a barely edible vegetable-based food item served in solitary called "the loaf" to a court, which as part of the agreement will no longer be served.

"Like me, I think New York got lost in 'the box,'" she said, referring to solitary in New York prison parlance. "Today we're finding a way out."