Many years before the Supreme Court in 1954, in Brown v. Board of Education, overruled the "separate but equal" doctrine, it appears that the unconstitutionality of that doctrine was suggested in two "friend-of-the-court" (amici curiae) briefs in Westminister School Dist. of Orange County v. Mendez, 161 F.2d 774 (9th Cir., 1947).

Those briefs were referred to by the court in its decision affirming the trial court judgment in Mendez v. Westminister, 64 F.Supp. 544, that the segregation of children of Mexican descent contrary to the laws of California violated the Fourteenth Amendment, as follows (161 F.2d at 780):

... There is argument in two of the amicus curiae briefs that we should strike out independently on the whole question of segregation, on the ground that recent world stirring events have set men to the reexamination of concepts considered fixed.... For reasons presently to be stated, we are of the opinion that the segregation cases do not rule the instant case and that is reason enough for not responding to the argument that we should consider them in the light of the amicus curiae briefs....

While the court did not identify the authors of those briefs, the record (161 F.2d at 775) shows that amicus briefs for both the NAACP and the ACLU were filed.

Samuel Krislov, in The Amicus Curiae Brief: From Friendship to Advocacy, 72 Yale LJ 694, at 712 states:

... Arguments that might anger the Justices, doctrines that have not yet been found legally acceptable, and emotive presentations that have little legal standing