You probably want to at least monitor their communications though; there is essentially no right to privacy for prisoners unless they are communicating with counsel. That means restricting the types of communication they can use (if only for practical reasons).

I think most people would agree we all want to avoid scenarios like this:

"Inside rolls of razor-wire fence, behind a network of heavy metal doors, locked alone in a North Carolina prison cell for 23 hours every day, a high-ranking gang leader directed accomplices in Georgia to carry out a contract killing. Step by step over a smuggled cellphone, the prisoner instructed gang members in chilling detail: “Gag him real tight. Put something in his mouth. Put something over his head.” The plot, to kill a prosecutor’s father, was foiled in April 2014. The inmate – a founder of the United Blood Nation – was sentenced in November to life plus 84 months on kidnapping and related charges." https://www.charlotteobserver.com/news/local/crime/article15...