I am against the death penalty except in two cases; murder/attempted while already in prison, or attempting to escape while in prison for murder/attempted.
If they are willing to sit in their cage without harming others, execution is a waste.
A simpler solution would be to build more cells and place only one prisoner in them while dividing meal times up among several small dining halls rotated throughout the day. Thereby you no don't have as many prisoner interactions without resorting to solitary confinement.
To this I would add both dividing large workout yards into five or six "slices" and policy of aggressive reassignment for prisoners who come into conflict to other areas of the prison, including an "unaffiliated wing" for prisoners who are confirmed gangless or defect from a prison gang and assist the prison's staff with information.
Oh yeah, and re-nationalize the fucking prisons, that would probably be nice too. Who the hell thought it was a good idea to give them to corporate entities? Have these people not read cyberpunk?
We know beyond doubt for a statistical and mathematical certainty that even if we have a 99.9% accuracy rate for conviction and sentencing. That means 1 person out of 1000 is wrongfully convicted, despite an absolutely excellent percentage of "getting the right person." There are millions of Americans incarcerated. There have been many condemned to die. Apply the same formula.... What result? Is this just? And, then realize that we do not have a 99.9% successful conviction rate of getting person who did the crime....
This is no radical theory. This is a rather old saying, "I should rather ten guilty men go free than see one wrongfully convicted."
I submit that no matter how horrible the crime, the punishment of execution imposed by the state is worse. Never mind entirely the fact that it's incredibly difficult to get an often legitimate insanity defense taken seriously or that often courts simply won't hear or take seriously several defenses and evidences of defendants. Crimes of these types are often rash acts of anger and though they are unjust, they are not committed by those asserting they are striving to be paragons of Justice.
Through execution, the state is also committing murder, but the murder it commits is far worse. Premeditated, prescribed killing done on ceremony and in the name of Justice, is hypocrisy. The state has the right to protect itself by separating dangerous members from it. Execution is not required for this, but rather is vengeance. There is no deterrence in execution, no example set to keep others from committing similar crimes of equal depravity. People have killed other people since the dawn of time and have been punished horribly for it. After thousands of years, this deterrence amounted to nothing. We call for blood, gallons of the stuff, in cries to calm our outrage. Those calls cannot beckon the dead to return.
No one seems to care. Call it nothing to worry about if you like. Heaven forbid you might care about it. I mean hey, let's say it's even only one person who is wrongfully executed. It's only one life in a system of millions of prisoners, except of course to that person when they say "but it was my life and I did nothing wrong to lose it...." If one innocent man must die for society's vengeance, no matter how justified, is that justice.
If one innocent man must die for society's vengeance, then it is not just for society to have that vengeance.