Because of the vital importance of counsel's assistance, this Court has held that, with certain exceptions, a person accused of a federal or state crime has the right to have counsel appointed if retained counsel cannot be obtained. That a person who happens to be a lawyer is present at trial alongside the accused, however, is not enough to satisfy the constitutional command. The Sixth Amendment recognizes the right to the assistance of counsel because it envisions counsel's playing a role that is critical to the ability of the adversarial system to produce just results. An accused is entitled to be assisted by an attorney, whether retained or appointed, who plays the role necessary to ensure that the trial is fair.
For that reason, the Court has recognized that the right to counsel is the right to the effective assistance of counsel. Government violates the right to effective assistance when it interferes in certain ways with the ability of counsel to make independent decisions about how to conduct the defense. Counsel, however, can also deprive a defendant of the right to effective assistance, simply by failing to render adequate legal assistance.
Strickland v. Washington, 466 U.S. 668 (1984) (internal citations and quotations omitted).