I think Miller's work demonstrates how true the statement actually is.  One of the most profound elements that emerges from the drama is the idea that guilt is decided in the court of public opinion or through political manipulation.  Miller's work is a testament to the importance of courts of law, meeting evidentiary burdens, and ensuring fairness in the judicial process as a part of determining justice.  When Salem devolves into a setting where accusations and political manipulation results in the deliberation of justice, there can be no honest pursuit of the end.  When social and political ends that serve individual self interest are critical elements in determining justice, I think that Miller's drama highlights that there can be no justice.  For Miller, the legal setting where checks and balances, the opportunity to be heard in a legal sense, as well as the basic idea of institutional configurations where fairness is evident, can only be where justice is achieved.