Final answer:
The decision in Gideon v. Wainwright requires states to provide counsel to felony defendants who cannot afford it. Also, Miranda v. Arizona mandates that police must inform suspects of their right to counsel during interrogations. Hence, it's unconstitutional for a state to deny a criminal appellant the right of self-representation.
Step-by-step explanation:
Under the landmark case of Gideon v. Wainwright, the Supreme Court of the United States unanimously held that state courts are required to provide counsel for defendants who cannot afford an attorney in all felony cases. The Sixth Amendment's guarantee of the right to assistance of counsel is a fundamental right applicable to the states via the Fourteenth Amendment's Due Process Clause. This decision overruled the prior precedent set by Betts v. Brady, which allowed states to deny counsel to indigent defendants in non-capital cases.
Additionally, the Miranda v. Arizona ruling established that the police must advise suspects of their right to remain silent and to have an attorney present during interrogations. Failure to provide these Miranda warnings before custodial interrogations may result in any confession or evidence obtained being excluded from trial. This ruling protects the Fifth Amendment right against self-incrimination and the Sixth Amendment right to an attorney.
Therefore, it would be unconstitutional for a state to deny a criminal appellant the right of self-representation, as both the right to counsel and the right to self-represent are protected under the U.S. Constitution.