In the majority opinion written by Justice Hugo Black, the Court held that, Since the Sixth Amendment constitutionally entitles one charged with crime to the assistance of counsel, compliance with this constitutional mandate is an essential jurisdictional prerequisite to a federal court's authority to deprive an accused of his life or liberty.

When this right is properly waived, the assistance of counsel is no longer a necessary element of the court's jurisdiction to proceed to conviction and sentence.

If the accused, however, is not represented by counsel and has not competently and intelligently waived his constitutional right, the Sixth Amendment stands as a jurisdictional bar to a valid conviction and sentence depriving him of his life or his liberty.

[3]This set the precedent that defendants have the right to be represented by an attorney unless they waive their right to counsel knowing full well the potential consequences.

Assistance of counsel was held to be requisite to due process of law in state felony proceedings with the Gideon v. Wainwright decision in 1963.