Photo courtesy of Derek Key via Flickr.

Solitary confinement of prisoners has exploded over the last few decades – despite the calls of human rights groups to label it an unconstitutional punishment.

America holds more prisoners than any other country in the world, despite only being home to 5% of the world’s population.

Criminal gangs and often squalid conditions have led to frequent prison violence, which in turn have led to a sharp rise in the amount of prisoners who are placed in solitary confinement.

What is solitary confinement?

Solitary confinement is the practice of holding prisoners isolated in individual cells for 22-24 hours a day, over periods ranging from days to decades, according to the non-profit Solitary Watch.

Prisoners in solitary are removed almost entirely from human contact, and are only allowed short periods of exercise in special outside areas.

Cells are often bare, windowless, and constantly lit, and the meals that arrive through slots in the door can sometimes be the only way to track the passage of time.

What are the effects of solitary confinement on prisoners?

Solitary confinement has been called “cruel and unusual” and “torture” by several human rights groups, which would make it illegal under the constitution.

The sensory deprivation caused by solitary confinement can both create and exacerbate mental health issues. Numerous studies have shown that even just a few days of complete isolation can lead to hallucinations, disorientation, anxiety and depression.

A 2014 study (pdf) in the American Journal of Public Health found that inmates in solitary confinement were 3.2 times more like per 1,000 days to inflict self-harm, and that 4% of prisoners surveyed were diagnosed with serious mental illness.

Prisoners that were detained in solitary conditions have been found to be more likely than others to commit crimes again, particularly if they were released directly from segregated housing.

Why are prisoners kept in solitary confinement?

While prisoner isolation has been a part of the U.S. penal system since penitentiaries were built in the 1700s, it didn’t occur on a large scale until increased prison violence in the ‘70s led to the rise of supermax institutions (pdf).

Proponents say “segregated housing” reduces violence by removing dangerous inmates from the general population, and keeps both prisoners and guards safer.

How many U.S. prisoners are in solitary confinement?

Data can be hard to track due to state-to-state variance in reporting requirements and definitions, but according to the Government Accountability Office (GAO), there are almost 15,000 solitary prisoners in the federal system alone – 7.1% of the total federal prison population.

In a 2005 Bureau of Justice Statistics report cited by the Vera Institute of Justice, it’s estimated that more than 81,000 prisoners are held in some form of “restricted housing,” another term for solitary.

Is the practice likely to change?

The practice of solitary confinement was almost banned as far back as 1890, when the Supreme Court called it and “infamous punishment” but stopped short of the “cruel and unusual” label that would deem it unconstitutional.

Debates over whether it constitutes torture are still ongoing. However, its usage has increased by 17% in federal prisons over the last five years, while total prison population only increased 6%

There are signs that attitudes might be changing, though:

The National Research Council has come out cautiously against (pdf) solitary confinement, while a Yale study concluded that while prison officials believe the practice makes institutions safer, it’s unclear “whether the policies are implemented as written, achieve the goals for which they are crafted, and at what costs.”

In the GAO report that noted the increase of solitary confinement in federal prisons, the office noted that “[The Bureau of Prisons] has not assessed the impact of segregated housing on institutional safety or the impacts of long-term segregation on inmates.”

The U.S. prison system is still something of a blind spot, with unclear data and reporting requirements between county, state, and federal institutions. As the issue of solitary confinement receives more attention, however, there will likely be more studies that shine a light on its wider impacts.