Final answer:
The Sixth Amendment is the constitutional amendment common to both Gideon v. Wainwright and Betts v. Brady, ensuring the right to counsel for defendants in criminal trials.
Step-by-step explanation:
The Sixth Amendment to the United States Constitution is the common link between the Supreme Court cases Gideon v. Wainwright and Betts v. Brady. This amendment guarantees the right to counsel for defendants in criminal trials, and its interpretation was central to both cases. In Gideon v. Wainwright, the Supreme Court held that the right to an attorney applies to both federal and state criminal cases and that indigent defendants must be provided with legal representation.
In Betts v. Brady, the Court ruled that the right to appointed counsel was not a fundamental right, which allowed states to decide when to provide legal representation. However, this decision was later overruled by Gideon v. Wainwright, where the Supreme Court held unanimously that the right to counsel in criminal cases is a fundamental right for a fair trial under the Sixth Amendment, leading to the requirement that states must provide attorneys to defendants who cannot afford legal counsel.
These landmark cases serve as essential referents for the constitutional right to legal representation and help to define the protections afforded under the Bill of Rights, specifically the Sixth Amendment, in the context of criminal justice and due process.