Digitized versions of physical books are supposed to make books more readily available to more people than ever before. In theory, replacing physical books with ebooks in prisons is also a great idea – inmates only need one device to access a wealth of content.

However, in reality, the US prison system is implementing this technology in a way that is raising some eyebrows in the advocate communities. A recent gathering of the National Conference on Higher Education in Prison (NCHEP) highlighted the issue of prison censorship and the growing practice of replacing books and libraries with ebooks and tablets.

Instead of providing those in the prison system with a chance to read books either for pleasure or education with no extra costs – like they are able to do with physical books donated by nonprofits or family – the tablets scheme is turning into a ruthless profit industry, several participants in an NCHEP panel have suggested on Twitter.

Prison Legal News, a magazine focusing on criminal justice issues, revealed in a tweet that inmates are being charged by the minute for ebooks they read on their tablets. These devices are sold by companies like JPay and GTL and controlled through their proprietary systems.

Inmates even have to pay for books downloaded from Project Gutenberg, that are offered to all users free since they're in the public domain, Books for Prisoners said.

The nonprofit added in one of the comments that – depending on the fee per minute and an inmate's reading speed – the cost of reading a single ebook could reach $25.

Another nonprofit, the Prison Policy Initiative, took an in-depth look at this problem in March, explaining that while the devices (with no internet access) are given to inmates free of charge – the companies who provide them make money not only on ebooks but also charge “above-market prices for phone calls, video chats, and media.”

According to the report, companies like JPay charge tokens they refer to as “stamps” for each email prisoners send using their tablets.

The contracts these companies are signing with US states allow them to change prices at will – and if the scheme is not profitable, to terminate their services.