> This resulted in killers like Charles Mason being relieved from execution and denying many victim's family member from obtaining a measure of justice they wanted.
That qualifies more as 'revenge' than as 'justice'.
The whole idea of a punitive system is broken at the foundation. Jail is not there to remove people from the pool (though in some cases that is a happy side effect), it is there to rehabilitate. In extreme cases this means people will never be released. But executing them makes 'us' just as bad as 'them'.
It should be there to rehabilitate, because (EDIT: in large part, there are other reasons) ultimately the vast majority of the incarcerated will be released back into society.
Unfortunately, the US has long since decided that punishment is the purpose, that these people are getting what they deserve. It's a very frustrating culture to be surrounded by.
And even if you don't accept that, just consider: most crimes aren't murder. They don't get people sent away for life, but for a period of 1-a few years.
They will be released back into society. If we do not rehabilitate them, we can expect recidivism from either failing to counter the errant impulses, exposure to similar or worse criminal elements while incarcerated, or failure to reenter society (due to ostracism, failure to adapt to changes, lack of social structure like family and friends). We are literally creating the problem by failing to rehabilitate criminals, and instead focusing on "punishing" them.
There is much to unpack in this topic, but I'll just point out that the idea that its purpose must be singular, one of punishment or rehabilitation, is a false dichotomy.
Justice is supposed to measured and balancing for society as a whole, meted out by an impartial judge and jury of peers.
Revenge is completely subjective and ruled by emotional responses by the aggrieved party. It's almost always going to be more destructive disproportionate than it needs to be.
The last people that should decide the fate of those who have harmed them are the victims. That just leads to pure chaos.
I could decide that if someone threatened my life that I would achieve justice by circumventing law enforcement and the justice system by murdering the person in question plus their whole family, whether they meant it or not. I could state reasons of personal/family honour and whatever other bullshit would justify those actions in my mind. That doesn't make it right, or just. It makes it a response borne of unchecked emotion.
You might say that is okay, but it would quickly lead to pure anarchy if we all followed that ideal. That's why we have a justice system in place that doesn't (or tries not to) focus on revenge.