Convicts sentenced lose a fraction of their rights, including the right to free speech.
"Under Turner, prisoner communication may be monitored and regulated, and the content of the communication (i.e., the legal advice) makes no difference in the assessment of the legality of the regulation."
"Under Turner, prisoner communication may be monitored and regulated, and the content of the communication (i.e., the legal advice) makes no difference in the assessment of the legality of the regulation."
http://en.wikipedia.org/wiki/Shaw_v._Murphy