[While law is on the agenda, this is a very good reminder that you can be wrong in many ways -- procedure and substance. Yoo is not alone in wanting to create his own law, we see that a lot. But, we can expect more from important legal advisors to the POTUS.]
When the Supreme Court ended the death penalty for mentally retarded offenders in 2002 and again for those who were minors at the time of their crimes in 2005, it did so via an elaborate interpretive dance that required putting one finger on the pulse of foreign courts and the other to the wind of American public opinion.
This* is not how I interpret Atkins (retarded) and Roper (minors). The former ruling handled things thusly:
Those mentally retarded persons who meet the law’s requirements for criminal responsibility should be tried and punished when they commit crimes. Because of their disabilities in areas of reasoning, judgment, and control of their impulses, however, they do not act with the level of moral culpability that characterizes the most serious adult criminal conduct. Moreover, their impairments can jeopardize the reliability and fairness of capital proceedings against mentally retarded defendants. ... Presumably for these reasons, in the 13 years since we decided Penry v. Lynaugh, 492 U.S. 302 (1989), the American public, legislators, scholars, and judges have deliberated over the question whether the death penalty should ever be imposed on a mentally retarded criminal.
Foreign courts did not really have much of a role in Atkins and the "evolving standards of decency" issue that is at the core of Dahlia Lithwick's 'national consensus' discussion only played a partial role. DL implies the Court mainly focused on foreign and domestic opinion; in Atkins, it did deal with one (the Constitution and judicial precedent required it) but even that only was part of the battle.
Roper addressed the matter this way:
Just as the Atkins Court reconsidered the issue decided in Penry, we now reconsider the issue decided in Stanford. The beginning point is a review of objective indicia of consensus, as expressed in particular by the enactments of legislatures that have addressed the question. This data gives us essential instruction. We then must determine, in the exercise of our own independent judgment, whether the death penalty is a disproportionate punishment for juveniles.
IOW, such "consensus" is important, but not the only thing at issue. The bottom line was that "The differences between juvenile and adult offenders are too marked and well understood to risk allowing a youthful person to receive the death penalty despite insufficient culpability." The world doesn't think much of the executive we have in place either. But, unlike cruel and unusual punishment, our Constitution allows that sort of system of government.
And, yes, foreign opinion is recognized. This is not new (the case referenced is from the 1950s) nor controlling:
This reality [foreign opposition to executing minors] does not become controlling, for the task of interpreting the Eighth Amendment remains our responsibility. Yet at least from the time of the Court’s decision in Trop, the Court has referred to the laws of other countries and to international authorities as instructive for its interpretation of the Eighth Amendment’s prohibition of “cruel and unusual punishments.”
References to foreign law and opinion might horrify some, but it is not really "originalist" horror per se. To take but an example, Martha Nussbaum in her latest book that deals with "liberty of conscience" notes that American political philosophy in the latter 1700s often took a "cosmopolitan" view ... we were "citizens of the world," who had a fundamental equality/kinship based on our ability to reason and have a capacity for moral judgment.
Thus, determining what is "cruel and unusual" is not just a matter of parochially looking at our own experiences, even if some wish to do that. This is a paltry view of the matter -- as if those in an age of enlightenment will only look for knowledge nearby. No, they have a decent respect for the opinions of mankind, to reference both the Declaration of Independence and a recent speech by John McCain.
But, again, this is just a factor in the judging involved, even if it might be something of a tie breaker in some fashion (or thumb on the scales). I agree finding a "consensus" is tricky, so we can focus on more concrete matters such as the lesser capacity of those mentally retarded or juveniles or the fact that the proportionality roughly expressed by "an eye for an eye" means that it is dubious to execute when someone did not take a life. So says precedent, and trying to suggest Coker didn't mean to include raping children is a dubious matter.
We can start with that, add another concrete problem raised in reply to an earlier post of mine on this topic -- often children make less reliable witnesses, so you might not have the firmness of proof necessary to "comfortably" execute someone. Also, though this might be more policy related, the death penalty might make it more complicated to prosecute or deal with rapists/protect children.
But, yes, determining "cruel and unusual" also includes some weighing of evolving standards of decency. This would likely be a factor (unspoken or not) in any extent, but it is not the sine qua non one here.
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* The link goes to the article this is directly in response to, but overall, my concern here the argument that the Supremes basically relies on what other countries (and some arbitrary analysis of national consensus) think on this matter and that even using this as a factor is illegitimate).