Final answer:
The Sixth Amendment's right to counsel applies to both federal and state systems due to Gideon v. Wainwright, incorporating this right through the Fourteenth Amendment's Due Process Clause to ensure a fair trial.
Step-by-step explanation:
The Sixth Amendment applies to both federal and state systems as a result of the Supreme Court's decision in Gideon v. Wainwright (1963). This landmark case established that the right to counsel is a fundamental right necessary for a fair trial and thus must be provided to defendants in state courts who cannot afford an attorney.
The defendant in the Betts case, and later in Gideon's case, cited the Fourteenth Amendment's Due Process Clause as the basis for requiring states to provide counsel. The rationale was that the due process clause guarantees the application of fundamental liberties, such as the right to counsel, by the states. The Supreme Court concluded that in the interest of ensuring fair trial and due process, states are obliged to appoint attorneys for defendants who could not afford one, thereby incorporation the Sixth Amendment right to counsel to apply to states.