Potter Stewart

“ Legislatures — state and federal — have sometimes specified that the penalty of death shall be the mandatory punishment for every person convicted of engaging in certain designated criminal conduct. Congress, for example, has provided that anyone convicted of acting as a spy for the enemy in time of war shall be put to death. ”

“ When people begin to believe that organized society is unwilling or unable to impose upon criminal offenders the punishment they "deserve," then there are sown the seeds of anarchy — of self-help, vigilante justice, and lynch law.
The constitutionality of capital punishment in the abstract is not, however, before us in these cases. For the Georgia and Texas Legislatures have not provided that the death penalty shall be imposed upon all those who are found guilty of forcible rape. [8] And the Georgia Legislature has not ordained that death shall be the automatic punishment for murder. ”

“ The instinct for retribution is part of the nature of man, and channeling that instinct in the administration of criminal justice serves an important purpose in promoting the stability of a society governed by law. ”