justice, morality, and the death penalty debate

Regarding one potential interpretation of the current LD resolution, reader Josh writes,

Common definitions of justice often include a degree of moral behavior. So I guess I am wondering what sort of moral behavior democracy offers that no other body can or does.

I'm not so much interested in the question--the answer, I would think, involves a respect for human dignity, as evidenced by the notions of popular sovereignty and equal rights, among other things--but in the complex interplay of morality and justice. Again, the resolution:

Resolved: A just society ought not use the death penalty as a form of punishment.

Because the resolution focuses on social justice, we should look to a legal framework where rights violations are settled in courts instead of on the street, by juries and judges instead of victims. A man is shot in a robbery. His brother might have an immediate moral claim on the life of the perpetrator, but, because of his respect for due process and the rule of law, refuses to take revenge, trusting in the machinations of justice.

Thus, even where fundamental moral and legal concerns intersect, legality must take precedence. Punishment may cause shame and express moral censure, and moral considerations might form the foundation of law, but both sides can argue that the primary purpose of punishment is to uphold the rule of law, both as an act of retribution and of communication. The death penalty's success or failure in this regard is up for debate.