If we can't have perfect confidence in the judicial system, we do not have the right to impose the ultimate penalty. Once someone is executed, you cannot undo an incorrect verdict. The death penalty had never been shown to be a deterrent to crime. Evidence suggests that he death permity may actually increase homicides. Neighboring states with the death penalty have higher murder rates that their neighbors without capital punishment.
Violence begets violence.
They found the state spent 2.16 million dollars per execution over imprisonment for life. Texas estimates it costs three to four times as much to execute a prisoner than to incarcerate them for 40 years. There are glaring racial inequalities in the way the death penalty is enforced. There are virtually no wealthy people on death row. Poor defendants often have inadequate legal defense.