The 6th Amendment, as with all amendments to the Constitution, is a way of protecting individuals against the violation of their inalienable rights by those in positions of authority. It also shows that the understanding of such rights within the Constitutional framework is formal, rather than substantive. In other words, it is concerned with spelling out what those rights are, as opposed to how they should be implemented.
The case of the 6th Amendment provides us with a particularly neat illustration of the formal/substantive distinction in relation to how natural rights are conceived. On the face of it, the guarantees it sets out are extensive, particularly when compared to other countries at the time. The fundamental principle is one we take entirely for granted today: the accused in every criminal prosecution has the right to an attorney for their defense. Otherwise, there can be no question of a fair trial. No one could seriously deny that this is indeed a very important formal right, one fundamental to any civilized society worthy of the name.
However, in terms of substance, the 6th Amendment does not always fulfill its own promise. In all too many cases, a proper legal defense is open only to those of sufficient means. Poor defendants often end up with public defenders, many of whom are incompetent, inexperienced, or poorly trained. The overall picture is even more disturbing in relation to cases involving the death penalty. According to a study by Columbia Law School, a large percentage of death sentence reversals are made on the grounds of inadequate legal representation.
Perhaps the main importance of the 6th Amendment lies in its purpose of serving as a standard of justice against which the actions of those in authority are judged and often found wanting. However, as with all other Constitutional amendments, it can do no more than gesture toward the specific public policy choices that society and its elected representatives must make in order to fulfill its huge promise and make its principles real.