True, the 8th Amendment restricts "cruel and unusual punishment." But if society progressed enough to consider the death penalty cruel and unusual then might that make it unconstitutional? According to those who go by the "living Constitution," not the originalists?
Discussion
I am not one.
If you would ascertain the meaning of legal documents in popular opinion rather than legal history, any US Amendment (or statute) might well outlaw or make mandatory any act.
The US Constitution references procedures for dealing with capital crimes, so it would be strange to inadvertently outlaw such procedures.
If memory serves me right, the Omnipotent Court-- I mean the Supreme Court--banned the death penalty in the past, unconstitutionally in my opinion, and this article even mentions the possibility of them doing that if it weren't for the current 6-3 conservative majority on the court.
I don't believe in the "living Constitution" either, but many in America do and accept the Supreme Court as our permanently-sitting, unelected constitutional convention...
Any court, even SCOTUS, operates in the long run by force of persuasion. Nonsensical decisions are sooner or later forgotten.
I think its possible, and I might consider such it preferable, but for it to be done right it would have to come as an advancement in common law. So if not having the death penalty was established throughout the land on say, a state by state basis, and it enjoyed widespread public support in those areas, and the logic and moral frameworks were robust enough to withstand criticisms, then it would be so.
As it stands, this isn't the case, many consider the death penalty to be right, and they have formidable arguments in its favor. I don't agree, I am not a fan of the death penalty, but I am against imposing a ban without establishing it as common law first.