What is the case law on affirmative action in the affirmative action context?

In a concurring opinion in Wygant, 476 U.S. at 284, 106 S.Ct. at 1852, Justice O'Connor harmonized the approaches individual justices had taken in that case and in prior cases to the showing defendants must make in supporting an affirmative action plan under attack. She said that while a public employer does not have to make findings that it engaged in past discrimination to implement an affirmative action plan, id. at 290, 106 S.Ct. at 1855 (O'Connor, J., concurring); see also Johnson v. Transportation Agency, 480 U.S. 616, 630 n. 8, 107 S.Ct. 1442, 1451 n. 8, 94 L.Ed.2d 615 (1987), it must have a "firm basis for believing that remedial action is required." Wygant, 476 U.S. at 286, 106 S.Ct. at 1853.

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