The whole works here.

Justice Scalia, dissenting, points out another case of "science" in the service of a political agenda (boldface mine):

Today's opinion provides a perfect example of why judges are ill equipped to make the type of legislative judgments the Court insists on making here. To support its opinion that States should be prohibited from imposing the death penalty on anyone who committed murder before age 18, the Court looks to scientific and sociological studies, picking and choosing those that support its position. It never explains why those particular studies are methodologically sound; none was ever entered into evidence or tested in an adversarial proceeding. As The Chief Justice has explained:

"[M]ethodological and other errors can affect the reliability and validity of estimates about the opinions and attitudes of a population derived from various sampling techniques. Everything from variations in the survey methodology, such as the choice of the target population, the sampling design used, the questions asked, and the statistical analyses used to interpret the data can skew the results." Atkins, supra, at 326-327 (dissenting opinion) (citing R. Groves, Survey Errors and Survey Costs (1989); 1 C. Turner & E. Martin, Surveying Subjective Phenomena (1984)).

In other words, all the Court has done today, to borrow from another context, is to look over the heads of the crowd and pick out its friends. Cf. Conroy v. Aniskoff, 507 U. S. 511, 519 (1993) (Scalia, J., concurring in judgment).

We need not look far to find studies contradicting the Court's conclusions. As petitioner points out, the American Psychological Association (APA), which claims in this case that scientific evidence shows persons under 18 lack the ability to take moral responsibility for their decisions, has previously taken precisely the opposite position before this very Court. In its brief in Hodgson v. Minnesota, 497 U. S. 417 (1990), the APA found a "rich body of research" showing that juveniles are mature enough to decide whether to obtain an abortion without parental involvement.