Mr. Justice Marshall, dissenting.
In Furman v. Georgia, 408 U.S. 238, 314 (1972) (concurring opinion), I set forth at some length my views on the basic issue presented to the Court in these cases. The death penalty, I concluded, is a cruel and unusual punishment prohibited by the Eighth and Fourteenth Amendments. That continues to be my view.
I have no intention of retracing the "long and tedious journey," id., at 370, that led to my conclusion in Furman. My sole purposes here are to consider the suggestion that my conclusion in Furman has been undercut by developments since then, and briefly to evaluate the basis for my Brethren's holding that the extinction of life is a permissible form of punishment under the Cruel and Unusual Punishments Clause.
In Furman I concluded that the death penalty is constitutionally invalid for two reasons. First, the death penalty is excessive. Id., at 331-332; 342-359. And [p. 232] second, the American people, fully informed as to the purposes of the death penalty and its liabilities, would in my view reject it as morally unacceptable. Id., at 360-369.
Since the decision in Furman, the legislatures of 35 States have enacted new statutes authorizing the imposition of the death sentence for certain crimes, and Congress has enacted a law providing the death penalty for air piracy resulting in death. 49 U.S.C. §§1472(i), (n) (1970 ed., Supp. IV). I would be less than candid if I did not acknowledge that these developments have a significant bearing on a realistic assessment of the moral acceptability of the death penalty to the American people. But if the constitutionality of the death penalty turns, as I have urged, on the opinion of an informed citizenry, then even the enactment of new death statutes cannot be viewed as conclusive. In Furman, I observed that the American people are largely unaware of the information critical to a judgment on the morality of the death penalty, and concluded that if they were better informed they would consider it shocking, unjust, and unacceptable. 408 U.S., at 360-369. A recent study, conducted after the enactment of the post-Furman statutes, has confirmed that the American people know little about the death penalty, and that the opinions of an informed public would differ significantly from those of a public unaware of the consequences and effects of the death penalty.
Even assuming, however, that the post-Furman enactment of statutes authorizing the death penalty renders the prediction of the views of an informed citizenry an [p. 233] uncertain basis for a constitutional decision, the enactment of those statutes has no bearing whatsoever on the conclusion that the death penalty is unconstitutional because it is excessive. An excessive penalty is invalid under the Cruel and Unusual Punishments Clause "even though popular sentiment may favor" it. Id., at 331; ante, at 173, 182-183 (opinion of Stewart, Powell, and Stevens, JJ.); Roberts v. Louisiana, post, at 353-354 (White, J., dissenting). The inquiry here, then, is simply whether the death penalty is necessary to accomplish the legitimate legislative purposes in punishment, or whether a less severe penalty—life imprisonment—would do as well. Furman, supra, at 342 (Marshall, J., concurring).
The two purposes that sustain the death penalty as nonexcessive in the Court's view are general deterrence and retribution. In Furman, I canvassed the relevant data on the deterrent effect of capital punishment. 408 U.S., at 347-354. The state of knowledge at that point, after literally centuries of debate, was summarized as follows by a United Nations Committee:
"It is generally agreed between the retentionists and abolitionists, whatever their opinions about the validity of comparative studies of deterrence, that the data which now exist show no correlation between the existence of capital punishment and lower rates of capital crime."
The available evidence, I concluded in Furman, was convincing that "capital punishment is not necessary as a deterrent to crime in our society." Id., at 353.
The Solicitor General in his amicus brief in these cases [p. 234] relies heavily on a study by Isaac Ehrlich, reported a year after Furman, to support the contention that the death penalty does deter murder. Since the Ehrlich study was not available at the time of Furman and since it is the first scientific study to suggest that the death penalty may have a deterrent effect, I will briefly consider its import.