If we weight lives against lives, how many of them has been lost by soft judgement? If there was 10 times more people dead by the hands of a former inmate, than innocent people executed, would that be enough of an argument?
Satius enim esse impunitum relinqui facinus nicentis quam innocentem damnari.No. The general idea on which the modern criminal law is construed is to make punishment rather swift and unavoidable than harsh. Also, it is not universal truth that all former inmates return to crime.
Death penalty or any permanent body injury is irreversible. That is why it should not be allowed. Also, (there many researches on that topic) - the death penalty does not prevent crimes, however the swiftness of the punishment does. I believe the societies should strive - permanently - to perfect the system, to cast the punishment fast, to avoid long criminal procedures, and to show that if someone commits the crime, the punishment is unavoidable. We do not need the death penalty to keep the dangerous people away from society.