In the case of Holmes v. California et al., 1962, the U.S Supreme Court ruled in favor of petitioner Robert Lee Holmes who was convicted for first-degree murder and sentenced to death by a California court. The issue at hand was whether or not his constitutional rights were violated when he was denied counsel during police interrogation after his arrest, which led to confessions that were used against him in trial. The Supreme Court held that under the Sixth Amendment's guarantee of right to counsel, it is unconstitutional for statements obtained from defendant during custodial interrogation without presence of an attorney to be admitted into evidence. This decision reversed and remanded Holmes' conviction back down to lower courts for further proceedings consistent with this opinion.

In the dissenting opinion for Holmes v. California, it was argued that the petitioner's constitutional rights were violated due to a lack of proper legal representation during his trial. The dissenting justices believed that there was an inherent conflict of interest when the same attorney represented both Holmes and another defendant in a related case, as this could potentially compromise their ability to provide effective counsel for each individual client. They also took issue with how evidence from other crimes committed by Holmes was used against him in court, arguing that this prejudiced the jury and denied him a fair trial. Furthermore, they disagreed with how certain statements made by Holmes were admitted into evidence without first determining whether or not these statements had been obtained voluntarily - which is required under federal law. Overall, they felt that several aspects of his trial did not meet constitutional standards for fairness and due process.