you can live they rest of your life content and with a clear conscience.
I would disagree. Somebody else would be living their (almost full) life with a clear conscience, merely utilizing your former body.
However, "Passing through Gethsemane" complicated the issue beyond simple "wipe and forget". It added a moment of uncertainty by telling that human-effected mindwipes would sometimes break.
Apparently, since an implanted personality would lack the complexity of a real personality... some hypothetical biological process of mental healing might "fix the old personality" instead of completing the new (as far as completing a biological mind would be possible without childhood).
Even parallel personalities might develop -- old personality healing, new personality completing itself. They would remain separated from each other. Only one would probably control conscious life. Unless a Centauri telepath came and "accidentally" established a bridge between them.
From the viewpoint of society, a biological healing process repairing the old personality... would have picked the wrong personality to help. From the viewpoint of self-preservation, it would naturally be saving its original (and by originality true, even if otherwise twisted) mind.
To avoid this... to make the new personality firmly root itself... would need careful and correct installation. Since humans (certainly current humans, and humans of Babylon 5) lack complete self-awareness and self-control (which we sometimes envy in computers) I suspect a human-installed "implanted personality" would often lack the finesse and complexity prevail on the ruins of a real personality (even a criminal one).
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I would suspect that implanted personalities installed by other, more experienced creatures... might have absolute and permanent hold over the brain they overtook. For example, within the confines of the fictional world of B5... I would not expect the core of a Shadow vessel to recover, even if parts of their old personality were knowingly left to exist.
On the issue of quick-and-dirty assemblies not having the complexity of self-assembled persons... even an implanted personality installed by Shadows (Anna Sheridan) failed. Admittedly in a far tougher task, namely impersonating a destroyed real personality.
Although in this case, impersonation was probably made impossible not by lacking finesse of installation, but lost source data and impossible goal (the real Anna would simply not have accepted the principles which the Shadows needed her to represent).
Their methods of overwriting a personality were probably irrevocable -- and some part of the previous Anna had been replaced beyond recovery by some low-grade shipmind. Low-grade enough to make a sentient shipmind feel nausea.
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On the issue of justice, in my eyes... aside from reforming where this is possible (if reforming demands external intrusion into the mind/body, the person choosing to reform must absolutely approve this before modification)...
...justice should stop the possibility of further crimes, make the criminal pay as exactly as possible... yet avoid (unless the criminal gets destroyed to prevent him/her from harming someone) death, irrevocable modification or cruelty.
Therefore, I would consider mindwipe (modification of mind with the expected result of destroying the old mind) an unacceptable punishment for any justice system.
You might ask why... if one goal is retribution... why avoid mindwipe? Why feed prisoners? Diffrent people might answer differently... feeding prisoners is certainly a burden on society. Posting a guard drone authorized to use lethal force after every criminal... would be inefficient too.
However, while people like to play society... they must admit the justice systems of societies can err. Mindwiping somone to later discover it destroyed an innocent person... would be just as good as completely killing an innocent person.
Detention is revocable. The term "mindwipe" implies it should not be, which makes it unacceptable except in defense of oneself or another from unjustified attack.