Why and how is prisoners rights a problem?

Inmates retain basic First Amendment rights (i.e., free speech and religion) only to the extent that the exercise of those rights do not interfere with their status as inmates. If the prisoner's attempt to exercise their First Amendment rights interfere with the legitimate objectives of the correctional facility, like like order, discipline, and security, they will generally be curtailed. As a result, prison officials can open incoming mail, read e-mails, and screen outgoing communications to ensure that it does not contain any messages that could interfere with the facility's objectives.

gregor's attempts to crawl on the walls