In the case of Mattox v. Sacks, Warden (1961), the U.S Supreme Court ruled in favor of petitioner Robert Lee Mattox who was convicted for murder and sentenced to death by an Ohio court. The issue at hand was whether or not a confession obtained from Mattox while he was under arrest but without counsel present violated his constitutional rights as per the Fifth and Fourteenth Amendments. The Supreme Court held that it did violate his rights because he had requested legal representation before being interrogated but this request wasn't honored. Furthermore, during trial, despite objections from defense counsel, this confession was admitted into evidence which led to his conviction - another violation of due process according to the court's ruling. As such, they reversed the judgment made by lower courts and remanded it back for further proceedings consistent with their opinion.

In the dissenting opinion for Mattox v. Sacks, it was argued that the majority's decision to grant a new trial based on newly discovered evidence contradicted established legal principles. The dissenting justices believed that such action should only be taken if there is reasonable certainty that an error occurred during the original trial which affected its outcome. They contended that in this case, even though some of the prosecution's witnesses had perjured themselves, their testimonies were not crucial to convicting Mattox and thus did not significantly affect his trial’s result. Furthermore, they pointed out inconsistencies in other aspects of Mattox's defense which cast doubt on his overall credibility and innocence claim. Therefore, they disagreed with granting him a new trial as they felt he failed to meet necessary criteria for one.