In Florida, where roughly 96,000 men and women are locked up in state prisons, the government’s list of 20,000 publications that are off-limits to inmates includes Klingon dictionaries, Dungeons & Dragons guides, prisoners’ rights pamphlets and Windows manuals “for Dummies.” Also listed are a host of coloring books — draw-between-the-lines titles featuring illustrations of butterflies, flowers, paisley patterns, “calming mandalas,” muscle cars and (in the case of “Exotic Chickens: Coloring for Everyone”) poultry breeds like the Crèvecoeur, Houdan, golden laced Wyandotte and Polish hen.

Under guidelines used by the Literature Review Committee at the Florida Department of Corrections, all those books are apparently “detrimental to the security, order or disciplinary or rehabilitative interests” of the state’s prisons, or “might facilitate criminal activity.” But what’s so bad about, for instance, a coloring book? In an email, a Florida corrections spokesman explained that some offer “easy to use templates for tattooing,” which is prohibited because of the risk of transmitting diseases. Foreign (and fictional) language dictionaries, meanwhile, can pose a security threat “by providing a method of communication not readily identifiable by security staff.”

The same books might be perfectly fine in another state. If that sounds arbitrary, it is. “There is a serious nationwide need for better standards and oversight in what prisoners are allowed to read,” says Michelle Dillon, public records manager and development coordinator for the Human Rights Defense Center, a prisoners’ rights organization based in Lake Worth, Fla. The group, which also runs Prison Legal News, a monthly magazine for inmates, published the Florida banned books list in July, as part of a larger effort to obtain similar lists from the Federal Bureau of Prisons and each state correctional system.

So far, the center has compiled full or partial lists from 20 states, not including publicly available lists for Pennsylvania and Washington state. Based on the group’s findings, the worst places for incarcerated readers include Texas — which made headlines in 2017 after it banned “Where’s Waldo?” but not Hitler’s autobiographical manifesto, “Mein Kampf” — as well as Arizona and Florida.

In Florida, prisoners can appeal a publication’s impoundment or rejection in the mail room by filing a grievance to the Literature Review Committee, a group of three prison officials that meets every two weeks; their decisions form the banned books list. But in Alabama and many other states, no systemwide review committee exists.

“What we’ve seen in the last 30 years is a dramatic clampdown,” says HRDC executive director Paul Wright, who founded the group after successfully challenging book bans as an inmate in Washington state. “Especially looking at self-help books. It almost harks back to the days of slavery, when it was illegal for slaves to learn to read or write, and a crime for anyone to teach them.”

His organization recently won a lawsuit against the Southwest Virginia Regional Jail Authority, which had required preapproval for all publications and barred HRDC magazines because the staples could be used as weapons or “tattooing guns.” But battles in the judicial system don’t always go their way. In January, the Supreme Court declined to hear an appeal of a case in which the group had unsuccessfully sued to overturn a ban on Prison Legal News in Florida jails. Officials argued that the publication’s advertisements, including for three-way phone-calling services, posed a security risk.

Most prisons do have libraries, which are often so underfunded and understaffed that inmates rely on reading material mailed by friends, family or nonprofits such as the Seattle-based Books to Prisoners. The organization sends about 12,000 packages each year to inmates asking for novels, dictionaries, Spanish-language textbooks and the like, amid byzantine prison regulations on what can be delivered.

Some of the rules, of course, make intuitive sense. Manuals on lock picking or improvised explosives are prohibited for obvious reasons. But plenty of the regulations are more questionable — or at least have unfortunate consequences. Many prisons ban hardcover books over fears that drugs might be hidden inside. And most states have strict rules on sexual content, leading to bans on art-history guides or works of literature like “The Color Purple” by Alice Walker and “I Know Why the Caged Bird Sings” by Maya Angelou.

Perhaps the most glaring example of prison censorship has been the rejection of books about criminal justice reform, mass incarceration and inmates’ rights. In a country where, according to the federal Bureau of Justice Statistics, black men serve prison sentences at nearly six times the rate of white men, books like Howard O. Lindsey’s “A History of Black America” and Henry Louis Gates Jr.’s “Finding Oprah’s Roots” have repeatedly run afoul of censors.

“Chokehold: Policing Black Men” by Paul Butler was banned in Arizona prisons until June, weeks after the American Civil Liberties Union threatened a lawsuit, and Michelle Alexander’s “The New Jim Crow,” a searing indictment of mass incarceration, was off-limits to prisoners in North Carolina, Florida and New Jersey before bans were lifted amid similar challenges by the ACLU. (Once again, “security” was cited to justify the bans. The New York Times reported that “The New Jim Crow” was barred from North Carolina prisons because officials determined it was “likely to provoke confrontation between racial groups.”)

Such books have proved transformative for readers like Jesse Dunaway, 38, whom I connected with through FAMM, an advocacy group that was formerly known as Families Against Mandatory Minimums. He began reading “The New Jim Crow” while in solitary confinement about five years ago, a decade into a life sentence for selling crack cocaine. “It woke me up,” he said by phone from Sussex II State Prison in Virginia. “It pretty much took me on a course where I’m fighting for my freedom” — that is, filing a petition for clemency.

If Dunaway is ever released, he will be one of the 95 percent of prisoners who eventually return home. “You have to ask yourself, ‘What kind of people do you want in your own community once they’re released?’ ” says Dillon. “Do you want people who have had access to these materials to expand their minds, or people who have had materials withheld from them for the past five, 10, 20 years?”

More from the Magazine:

Are goats the new weed whackers? Plenty of people want them to be.

Army recruiters released their first rap video. It wasn’t exactly a mic drop.

What should you look for in the Democratic debates? Ask the man who prepped Gore and Kerry.