IF YOU are reading this in a prison in Missouri you probably didn't receive the June 29th issue of The Economist (pictured at right). For this we apologise, though it wasn't our fault. We recently received a letter from the Missouri Department of Corrections informing us that the issue had been censored.

Was this a pre-emptive strike against our editorialising on prison reform? Were Missouri officials unhappy with our endorsement of Barack Obama? Do they hate puppies? Up until 1974 any of those reasons might have been used to restrict prisoner mail. But that year the Supreme Court ruled that officials in California were violating prisoners' first-amendment rights by censoring mail for arbitrary reasons, like its political or religious content, or because it criticised the prison itself.

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So what gives, Missouri? According to the letter, prisoners were not allowed to receive the June 29th issue because it

1. constitutes a threat to the security or discipline of the institution;

2. may facilitate or encourage criminal activity; or

3. may interfere with the rehabilitation of an offender

Those are heavy charges (no wonder a subscription costs so much). The censorship committee specifically referenced page 28, on which this article appeared. The piece takes a nuanced look at two contentious Supreme Court rulings on voting rights and college admissions. Did the committee think prison progressives might riot?

No, the panel was more likely concerned with the image of a Ku Klux Klan member holding a noose that ran alongside the article. That would explain its contention that the issue "contains information which can be used to instill violence or hatred among the offender population". It's a bit of a stretch, but one could imagine some of the nuance of the article being lost if, say, a white inmate were to shove the picture of the Klansman in the face of a black prisoner.

The Supreme Court has given prison officials wide latitude to restrict mail in this way. While the court acknowledged prisoners' first-amendment rights in 1974, it gave more weight to "security, order, and the rehabilitation of inmates". It was actually a case involving inmates in Missouri, in 1987, that prompted the court to rule that the "strict scrutiny" standard of review wasn't necessary when considering prisoners' rights. A new regulation only had to be reasonably related to legitimate penological interests.

Using this lower standard, the court ruled in 2006 that periodicals could be denied to prisoners in order to induce better behaviour. Lower courts have found that it is okay to restrict pornography in order to reduce sexual harassment of female guards. It therefore seems perfectly reasonable that mail be restricted on the grounds that it might incite racial or religious violence.

Some of you may be wondering, since The Economist does not advocate racial or religious hatred (thank you for noticing), why didn't prison officials simply cut out the offending picture, or remove the offending page. Some 16 years ago, when an inmate named Isa Shabazz was denied his copies of Muhammad Speaks magazine, an appeals court asked the same question. "It is not clear why it was necessary to deny the entire issue", stated the court in remanding the issue back to a lower court.

The lower court, though, sided with the prison, which argued that "the costs to implement such a procedure would be prohibitive". A cursory economic analysis finds fault with that argument, considering the censors are already paid to spot offending material. Anyway, this is small fry compared to America's bigger problem of overcrowded prisons. Inmates, we hope, will be able to read about that in the current issue.