Locks on reading between the bars

Tens of thousands of books are banned from US prisons, with authorities citing vague "security" fears or worries over sexual content for the bans, which prevent some of America's 1.2 million inmates from reading often innocuous-sounding texts.

A study by free expression group PEN America, finds widely differing and often inconsistently enforced policies resulting in a "staggering" number of books being banned.

Victims of the censorship include The Girl with the Lower Back Tattoo, Sun Tzu's classic manual The Art of War and the century-old tract The Use of Ropes and Tackle.

"Bans for purported sexual content are applied extremely broadly, from books on menopause to issues of Cosmopolitan and Rolling Stone, to art and medical books," PEN says in Reading Between the Bars.

Florida is the most enthusiastic censor, refusing 23,000 titles.

Robert Blankenship, incarcerated in Virginia, notes that in Virginia prisons Game of Thrones novels are banned, but his prison airs the full, unedited HBO series on facility televisions.

The most censored title is Prison Ramen, a cookbook banned in 19 states.

Its recipes can be made in a cell.