The Kansas regulation prohibits all "sexually explicit" material, define thus:
"The material shall be considered sexually explicit if the purpose of the material is sexual arousal or gratification and the material meets either of the following conditions: ...So, not only visual depictions of nudity or sex are banned, but also any prose that describes sex if its purpose is deemed to be titillating. Several books that Mr. Washington ordered were censored as sexually explicit: Slave Girl by Claire Thompson, a smutty novel about consensual dominance and submission within marriage; Yearbook Lingerie 2004: Objects of Desire by Elodie Pivateau, apparently a serious fashion photo book; The Lapdancer by Juliana Beasley, a serious if apparently explicit book of photojournalism by an art student-cum-stripper; How to Make Love Like a Porn Star by Jenna Jameson, the superstar's lurid and "cautionary" memoir; The Sexual Life of Catherine M. by Catherine Millet, the noted French art critic's shockingly graphic and introspective memoir; and The Bride Stripped Bare by Nikki Gemelli, an acclaimed and bestselling British novel, originally published anonymously.
(2) Contains any display, actual or simulated, or description of any of the following: (A) Sexual intercourse or sodomy...(B) masturbation..."
Of these, my guess is that only the first can fairly be said to be intended primarily for sexual gratification; the rest are more or less "serious" literary or nonfiction books, though no doubt possessed of a substantial titillation factor for men in prison. It appears the state's own policy wasn't being followed, as I was able to make these calls with some confidence with a quick Amazon check. The folks in the prison mail room could no doubt make similar judgments just as quickly. Still, the court rejected arguments that prison officials should be ordered to give more careful consideration to possible "explicitly" books, saying this would be too burdensome.
The court's justifications for the policy are twofold: (1) any sexually explicit material in the prison is likely to fall into the hands of sex offenders, and it's dangerous for sex offenders to read it, and (2) sexually explicit material encourages and becomes a tool of sexual harassment of corrections officers. Now, the standard here is "legitimate penological justification" - it's a low bar, scarcely more than rational-basis review. But the court does seem to take it as self-evident that sexual material of all kinds must be kept out of the hands of sex offenders - logic that I've previously opined is deeply suspect. The sexual-harassment rationale seems less flimsy, at least as applied to photographic or illustrated material, but I'm not sure the argument is as strong that explicit prose will facilitate harassment of prison staff.