In the case of Procunier, Corrections Director, et al. v. Navarette in 1977, the United States Supreme Court ruled on a matter concerning prisoner rights and censorship within prison systems. The plaintiff was an inmate who had filed a lawsuit against California's Department of Corrections for censoring his mail without notifying him or giving him an opportunity to protest this action. The court held that while prisons may have legitimate reasons to inspect and even censor certain types of correspondence under specific circumstances (such as maintaining security), they must also provide procedural safeguards to protect inmates' First Amendment rights whenever such actions are taken. These safeguards include providing notice when any censorship occurs and offering some form of review process where prisoners can challenge these decisions.

In the dissenting opinion for Procunier v. Navarette, Justice William J. Brennan Jr., joined by Justices Thurgood Marshall and Potter Stewart, argued that the majority's decision to uphold prison officials' right to censor inmate mail violated First Amendment rights of free speech. They contended that censorship should only be allowed if it is necessary to maintain security and order within prisons or protect public safety - a standard they believed was not met in this case. The dissenting justices also criticized the majority for failing to provide clear guidelines on what constitutes "legitimate penological interests," thus leaving too much discretion in the hands of prison officials which could lead to arbitrary decisions and potential abuse of power.