Under what condition is a person's right to legal counsel guaranteed?

A person's right to legal counsel is guaranteed in all criminal prosecutions because the Sixth Amendment of the U.S. Constitution explicitly states that individuals have the right "to have the Assistance of Counsel for his defence." This provision ensures that anyone facing criminal charges has the opportunity to obtain legal representation, which is vital for a fair trial. The right to counsel helps to uphold the principles of justice by ensuring that defendants can adequately defend themselves against the state, which often has significant resources at its disposal.

This right applies universally in the context of criminal proceedings, regardless of the severity of the charges. While the other options may refer to specific contexts where legal representation is important, they do not capture the comprehensive guarantee of counsel that exists under the Sixth Amendment in all criminal cases.