These decisions emulate Brandeis’ classic effort to demonstrate that the "law in books" was out of touch with the "law in action" in a variety of cases. Footnote #11 in Brown v. Board of Education, for example, "was merely a list of seven works by contemporary social scientists, all of which had been cited in the NAACP briefs during litigation of the school cases." It demonstrated the "badge of inferiority" that racial segregation produced. To Justice Warren, "it had seemed an innocuous enough item to insert in the opinion. ‘We included it because I thought the point it made was the antithesis of what was said in Plessy,’ he later commented. ‘They had said there that if there was any harm intended, it was solely in the mind of the Negro. I thought these things - these cited sources - were sufficient to note as being in contradistinction to that statement in Plessy.’" [Richard Kluger, Simple Justice: The History of Brown v. Board of Education and Black America’s Struggle for Equality (1975), 705-707].

In more recent times, the Assisted Suicide Cases before the Supreme Court brought forth empirical studies of how other societies deal with "the right to die." In Washington v. Glucksberg (117 S. Ct. Rep. (1997) 2258, 2291-2292) Justice Souter turned to various studies of the guidelines now in place in the Netherlands, "the only place where experience with physician-assisted suicide and euthanasia has yielded empirical evidence about how such regulations might affect actual practice." Justice Souter acknowledged, however, that "[t]here is ... a substantial dispute today about what the Dutch experience shows."