[Lurking Libertarian]

Study the case law, and find out.

I have. I have been a lawyer for more than 30 years and I have represented defendants in criminal cases.

Incarcerated prisoners are held essentially to have lost all of their rights until and unless a State or Federal Supreme Court decides otherwise.

Nope; "a prisoner retains all the rights of an ordinary citizen except those expressly, or by necessary implication, taken from him by law." Coffin v. Reichard, 143 F.2d 443, 445 (6th Cir. 1944).

[morphing libertarian]

My 22 also lists another standard for rights restriction. Basically to need to safely operate the prison system. I am sorry it’s been awhile and i don’t have a specific cite.

[FredZarguna]

COFFIN v. REICHARD is binding on nobody outside of the Sixth Circuit, but is not in conflict with my statement; IT IS IN CONFLICT WITH YOURS. The Constitutional rights of incarcerated persons may be circumscribed by law; those of ordinary citizens may not be. The laws circumscribing prisoners rights remain in effect essentially until a State or Federal Supreme Court decides otherwise.

Seven years after Coffin, the Ninth Circuit, in STROUD v.SWOPE found that "We think that it is well settled that it is not the function of the courts to superintend the treatment and discipline of prisoners in penitentiaries, but only to deliver from imprisonment those who are illegally confined."

You should read Stroud, a decision which impinged directly on the claimants right to "free speech." The concurring opinion is particularly damning to your position.