The New York City Council has voted in favor of banning most uses of solitary confinement in city jails, which could put a near-total end to a controversial practice that has been used for centuries.

Solitary confinement, also called punitive segregation, is a form of punishment in which an prisoner is detained to a single cell for most of the day — though there have been several instances in which detainees are held for long periods of indefinite isolation.

With a vote of 39 to 7 on Wednesday, the City Council passed a measure to ban the use of solitary confinement beyond a four-hour “de-escalation” period during emergencies, such as when a detainee has caused harm to someone else or is at risk of doing so. The measure also calls for detainees to spend at least 14 hours outside of their cells each day.

The bill follows scrutiny over deaths reported at the Rikers Island jail complex and in various facilities across the city, some of which were linked to prolonged use of solitary confinement, NBC News reported.

Nationally, the use of solitary confinement has divided communities, with detractors arguing that it is torture and backers upholding it as a legitimate form of punishment for detainees who break prison rules.

The New York measure can only take effect if signed within the next 30 days by Mayor Eric Adams, who appears to have reservations. However, two-thirds of the city’s legislative body supported the bill and signed on as co-sponsors, indicating that it has the power to override a veto, NBC News reported. This week, Adams told reporters that he doesn’t believe in solitary confinement but also doesn’t like the bill’s current form.

Despite a vote from the Board of Correction, which oversees New York City’s jail system, to end solitary confinement in 2021, politicians and activists have insisted that the practice continues, NBC News reported.

During a City Council hearing last year, city jail officials said that 117 of 6,000 detainees were held separately, maintaining that it’s an important tool to ensure safety when dealing with violent inmates, The New York Times reported. Adams echoed those concerns, saying the measure could make jails less safe.

“This assault on public safety is just wrong,” Adams said on Wednesday after the vote, according to The Times. “There is a philosophical difference in this city, and the numerical minority is controlling the narrative.”

More than a decade ago, a United Nations official said that solitary confinement should be banned in the U.S., explaining that “it can amount to torture or cruel, inhuman or degrading treatment or punishment when used as a punishment, during pretrial detention, indefinitely or for a prolonged period, for persons with mental disabilities or juveniles.”

Studies show that people of color, specifically Black and Latino people, are more likely to be perceived as a threat and subjected to solitary confinement.

According to the American Civil Liberties Union, the punishment has been found to cause serious psychological damage, increased mental health issues and other forms of harm among incarcerated people, especially disabled inmates. Nearly 50% of suicides by incarcerated people have occurred in solitary confinement.

According to a report from the Columbia University Center for Justice, the New York City Department of Corrections’ most recent forms of solitary confinement have placed people in structurally restrictive housing and repeatedly locked up inmates for much longer than the six-hour limit.

“No matter what terminology you use, there is isolation that the U.N. has called torture, and that is what we want to end,” New York City Public Advocate Jumaane Williams, who helped introduce the measure last year, told reporters ahead of the City Council’s vote, according to NBC News.

“We want to make sure that the psychological effects that are proven are not something that is done in the city, and hopefully, across the country,” Williams said.

Opponents of solitary confinement have advocated for alternatives such as incentive- and program-based forms of separation for inmates rather than isolation. Separation has been found to be more effective and safer for not only the incarcerated people but also for jail staff and communities.

According to Solitary Watch, 45 states in the U.S. have introduced bills to regulate, limit or ban solitary confinement, and 25 states have introduced bills to limit solitary to 15 days or less. Three bills have passed. Action has also been taken on a federal level to address solitary confinement, with bills in both the Senate and the U.S. House introduced this year to ban its use in federal prisons.