Long-term solitary confinement, in which a prisoner is cut off from almost all human communication for an extended period of time, is practiced almost exclusively in the United States. While many challenge the benefits of solitary confinement, others argue that it is necessary for some high-profile and dangerous criminals.
Solitary confinement was first tried in the United States at Eastern State Penitentiary in Philadelphia. Solitary confinement was thought to encourage prisoners to reflect on their crimes and reform, but it often led to suicide and insanity. Now, temporary solitary confinement is primarily used for prisoners who are considered too dangerous to themselves or others to mix with the general prison population, though new "Super Max" prisons keep violent or high-profile prisoners confined for 23 hours of the day, leaving one hour for exercise or visits.
The most evident "con" of solitary confinement is the negative effect on mental health that being cut off from human contact can have on inmates. In the early years of solitary confinement, researchers noted increased suicide and mental illness among prisoners. Studies have also found that solitary confinement harms parts of the brain -- solitary confinement can cause the brain to be as impaired as the brains of those who have undergone traumatic head injury. Inmates who have undergone long-term solitary confinement often become listless, apathetic and depressed.
The biggest reason for the use of solitary confinement is when prisoners are dangerous to others. Supporters of solitary confinement argue that some prisoners need to be separated from society at large for their own safety and the safety of others.
Solitary confinement can also make it more difficult for inmates to integrate themselves back into society, as solitary confinement can cause inmates to lose the ability to regulate their lives and have normal interactions with people. Studies also show that inmates who have undergone solitary confinement are more prone to bouts of severe anger and depression, both conditions that are likely to cause recidivism.