George Will has decided it's time to end capital punishment:
The conservative case against capital punishment, which 32 states have, is threefold. First, the power to inflict death cloaks government with a majesty and pretense of infallibility discordant with conservatism. Second, when capital punishment is inflicted, it cannot later be corrected because of new evidence, so a capital punishment regime must be administered with extraordinary competence. It is, however, a government program. Since 1973, more than 140 people sentenced to death have been acquitted of their crimes (sometimes by DNA evidence), had the charges against them dismissed by prosecutors, or been pardoned based on evidence of innocence. For an unsparing immersion in the workings of the governmental machinery of death, read “Just Mercy” by Bryan Stevenson, executive director and founder of the Equal Justice Initiative.
Third, administration of death sentences is so sporadic and protracted that their power to deter is attenuated. And expensive, because labyrinthine, legal protocols with which the judiciary has enveloped capital punishment are here to stay. Granted, capital punishment could deter: If overdue library books were punishable by death, none would be overdue. But many crimes for which death is reserved, including Tsarnaev’s crime of ideological premeditation, are especially difficult to deter.
Elizabeth Price Foley isn't buying it and quotes an opinion by an Oregon district attorney, who notes that there is a wrongful conviction rate of "only" .28 of 1 percent:
The wrongful conviction rate should be lower and prosecutors can do more than anyone in the criminal justice system to make sure that happens by being very discriminating in bringing capital cases. Pharmacists and doctors separately kill 10,000 Americans—by accident—every year, but we don’t ban prescriptions or elective surgery. We try to find out what went wrong and fix it.
That's what I'd call a faulty analogy. People treated by pharmacists and doctors have something wrong with them -- it's "the right person" but just a mistaken treatment. Those getting unfairly executed are not the right person.
She also says it the death penalty can be a deterrent, which I rather doubt given how haphazardly it is carried out (except that, of course, it deters the one person it is being applied to.)
But she is right that there is no constitutional argument against the death penalty. The plain language of the Constitution makes it clear that the founders thought about the issue and did not consider it cruel and unusual punishment.