Recently I've had an exchange of e-mails with Ms. Diann Rust-Tierney, Executive Director of the NCADP (The National Coalition to Abolish the Death Penalty). One thing Ms. Rust-Tierney wrote really opened my eyes.
There will always be people who believe the death penalty is not morally abhorrent -- but these people can come to see and agree with us that the death penalty should be repealed-- either because it is more trouble than it is worth or because the other harms that it causes outweigh any measure of good they believe the death penalty provides.
The following video really captures the idea of harm outweighing good. It closes with a wonderful quote from the former Supreme Court Justice, William J. Brennan, Jr.
"We remain imprisoned by the past as long as we deny its influence on the present."