Final answer:
The Sixth Amendment guarantees the right to an attorney, which was emphasized in the Gideon v. Wainwright case, where the Supreme Court ruled that states must provide legal counsel to defendants who cannot afford one.
Step-by-step explanation:
The Sixth Amendment of the United States Constitution guarantees the right to legal counsel, which includes the provision of an attorney for defendants who cannot afford one. This was firmly established in the landmark Supreme Court case of Gideon v. Wainwright. In this 1963 case, the Court unanimously held that the Constitution requires state courts to provide attorneys for defendants charged with serious crimes if they cannot afford counsel on their own. This ruling was based on the principle that a fair trial cannot be guaranteed without the assistance of counsel.
Clarence Earl Gideon, a poor drifter, was convicted of a felony after being denied a lawyer. He appealed to the Supreme Court by writing a handwritten petition. The Court's decision in his favor extended the right to counsel for felony defendants in state courts, fundamentally changing the criminal justice system and ensuring the right to a fair trial for all, regardless of their ability to pay.
Later, the Gideon ruling was expanded to include any case where there is a possibility of imprisonment, which raised the need for competent public defenders or pro bono legal representation, massively impacting the court system and defendants' rights.