Final answer:
The Sixth Amendment guarantees the right to legal counsel for indigent defendants in both federal and state courts, as established in the landmark case of Gideon v. Wainwright. This principle ensures that individuals accused of serious crimes have access to legal representation, even if they cannot afford an attorney.
Step-by-step explanation:
According to the Sixth Amendment of the U.S. Constitution, defendants in criminal cases have the right to have a lawyer provided to them if they cannot afford one, a principle known as 'in forma pauperis'. This guarantee applies to both federal and state courts. The Supreme Court case of Gideon v. Wainwright in 1963 established that indigent defendants accused of serious crimes must have access to legal representation, regardless of their ability to pay.