In the case of Costello et al. v. Wainwright, Secretary, Florida Department of Offender Rehabilitation et al., 1976, the U.S Supreme Court addressed a petition by two inmates in a Florida state prison who claimed their constitutional rights were violated due to censorship and interference with their mail by prison officials. The inmates argued that this was an infringement on their First Amendment rights to freedom of speech and expression as well as a violation of their Fourteenth Amendment right to equal protection under law. However, the court ruled against them stating that such restrictions were necessary for maintaining order and discipline within prisons and did not violate any constitutional rights provided they are applied fairly without discrimination or favoritism towards any particular group or individual.

In the dissenting opinion for Costello et al. v. Wainwright, Justice Brennan disagreed with the majority's decision to deny federal habeas corpus relief to state prisoners who claimed that their guilty pleas were involuntary due to ineffective counsel. He argued that a defendant should not be required to prove "prejudice" in order for his plea of guilt to be considered involuntary and thus unconstitutional under the Sixth Amendment right-to-counsel guarantee. Instead, he believed any deficiency in legal representation which could have affected the voluntariness of a plea should suffice as grounds for granting relief without needing further proof of prejudice or harm caused by such deficient performance.