Officials in prison systems across the United States have banned certain books as a way to prevent the flow of material that they say might incite violence.

In Michigan, the ban has extended to several non-English language dictionaries.

Over the last year, the Michigan Department of Corrections has banned dictionaries in Spanish and Swahili under claims that books' contents are a threat to the state's penitentiaries.

"If certain prisoners all decided to learn a very obscure language, they would be able to then speak freely in front of staff and others about introducing contraband or assaulting staff or assaulting another prisoner," said Chris Gautz, the spokesperson for the Michigan Department of Corrections.

He says allowing prisoners to gain access to language books other than English could encourage them to organize without the knowledge of staff.

"When it's in a language that we don't have the ability to read ourselves and understand exactly what it is that we're looking for, we're not able to allow it in," he added.

If staff is unable to find a translation the book request is denied, and the book is placed under the list of banned books – even when these are in Spanish. The second most spoken language in American households.

For Rodolfo Rodriguez getting books in his native Spanish language has been about learning how to communicate in English. Something he says he's been trying to do since his life sentence in 1993.

"One feels offended. One feels like they are telling you that pure Spanish is worthless, that you don't need to learn because you'll just stay here," he said in a call from Lakeland Correctional Facility in southern Michigan.

Because he doesn't speak and write well in English, Rodriguez says he's had a harder time navigating the legal process from prison.

Seven books in both Spanish and Swahili have been banned from the state's prisons in the last year, according to a list obtained through a Freedom of Information Act request.

Kwesi Osundar was born in Detroit and has been requesting books in Swahili since 2009. He says he's been wanting to learn more about the African diaspora.

"So Swahili being one of the more widely spoken African languages that was the first stop for me," he said. He is at Chippewa Correctional Facility in northern Michigan.

Osundar says he's filed grievances with the prison, but these never went anywhere.

"It's just there because they have to give us some form of process to seek administrative remedies, but very seldom does anybody get any relief," Osundar explained.

But prison's spokesperson, Gautz, says the issue of banning language books isn't something that's come up a lot.

"If we were to start seeing requests, and the need to have something be reviewed along these lines, we could certainly be open to that," he said.

Paul Wright, the director of the Human Rights Defense Center and a former inmate at a correctional facility in the state of Washington, has been dealing with censorships at prisons across the United States for the last two decades.

While he was incarcerated, Wright founded Prison Legal News, a publication that he's fought to keep from being censored.

"Prison officials like to censor anything that's critical of themselves, and also they like to censor anything to do with minority anything," he said.

A 1989 Supreme Court ruling allows prisons to ban any book – as long as it's in the interest of safety.

Rodolfo Rodriguez would like the Michigan policy on books in different languages revised. He says incarcerated people deserve a right to educate themselves in their own native language.