By keeping a person locked up for life, which may well be appropriate for the “worst of the worst”, they are incapacitated for life. It similarly satisfied any retributive instinct, providing a total punishment, a form of internal banishment and total civil death – if one considers retributive justice desirable.  Moreover this is inconsistent. If we are inflicting an eye for an eye because they deserve it then why should the death penalty reserved for the worst of the worst? Should it not be exactly proportional – which would mean all murderers should face the death penalty.