Sometime in the future, science determines the exact brain chemistry/anatomy which leads to violent psychopathy. I.e., the thing which leaves certain people devoid of empathy and with the impulse to kill, right from birth. And medicine has advanced to the point where removing psychopathy is a trivial procedure; a few hours in a hospital, and a former psychopath walks out with normal empathy, their impulse to kill extinguished, and even remorse for anyone he or she may have murdered prior to the procedure. This procedure is safe, reliable, of negligible cost, devoid of side-effects, and even has a genetic component so that any future children the former psychopath has will be normal.
When a violent psychopath is caught and convicted of murder, is the future society obligated to punish the criminal — via prison sentence, execution, or any other means -- if he or she is willing to undergo the procedure? EDIT: Why or why not?