ANY fan of cops-crooks-and-courtrooms dramas knows that solitary confinement is a treat reserved for highly volatile criminals, or used to punish inmates for various misdeeds. In 2011, after determining that more than 15 days without human contact can have serious effects on a prisoner's mental health, a special rapporteur for the United Nations' Human Rights Council officially recognised prisoner isolation as a form of torture.

But what about isolation by langauge? Few have acknowledged the effects of language barriers in prisons, which can cut off prisoners from meaningful human contact for long stretches. The closest America has come to addressing this issue is through its Crime Control Act of 1990, which requires that inmates in federal prisons take English language classes until they reach the proficiency of an eighth grader. But this does not apply to individual states, nor to irregular prisons like the one at Guantánamo Bay, where a prisoner may not be considered "isolated" if others are physically present. Anyone who has gone even a day without speaking to another person, though, knows that this is real solitude, even when others are around. How exactly does linguistic isolation affect the psyche?

In a recent paper, Peter Jan Honigsberg of the University of San Francisco law school has taken a step toward answering this question. In "Alone in a Sea of Voices: Recognizing a New Form of Isolation by Language Barriers", Mr Honigsberg compares physical and linguistic isolation, and found the similarities uncanny. In the most notable example, Honigsberg described a 16-year-old boy who spent eight years at Guantánamo after 9/11 because no country would have him, despite his quickly-discovered innocence. During those years, he was surrounded by prisoners who only spoke English or Arabic, while he knew only Uzbek. He was given no materials to help him learn English or Arabic, and no translator after his initial imprisonment. This resulted in a loneliness so acute that he cried every time he woke up. Mr Honigsberg wrote that this situation is akin to the anguish experienced by a stroke victim who is surrounded by conversations, but cannot participate. In immigration facilities, the same problems pertain, but are less severe, as prisoners spend less time there. Nonetheless, those suffering from language isolation experience disorientation and a decline in their decision-making ability.

This has not gone completely unnoticed. The European Council's European Committee in Crime Problems, for example, has said that the "inability to communicate in the language most commonly spoken in a prison is a severe barrier to foreign prisoners' ability to participate in prison life. It is the root cause of many problems such as isolation." But the council can only recommend, not require, its member states to take action.

Of course, language isolation will affect different people in different ways. If someone is naturally quick at picking up languages, his or her isolation will be short-lived and therefore not as hard to bear. But many prisoners will not be so gifted. And the problem is exacerbated in prisons that allow only one language to be used. Mr Honigsberg gives the example of a European Court of Human Rights case in which a Tajik inmate in a Russian prison was only allowed to speak Russian, even when his family came to visit. The court found that this "violated Article 3 of the European Convention of Human Rights, prohibiting torture or inhuman or degrading treatment or punishment".

The UN's 2008 report on solitary confinement states that "the practice has a clearly documented negative impact on mental health," mentioning insomnia, confusion and hallucinations, "and therefore should be used only in exceptional circumstances." While the isolation felt due to language barriers may be dulled slightly because there are other people nearby, policymakers should nonetheless take it seriously. Humans have an inherent need to communicate, and to be denied this need is to be denied a fundamental right.