The consequences of Griggs v. Duke more complicated than that: the problem with IQ tests is that they are slippery. An employer can say "we want the best and brightest." And they can decide that a degree from Stanford meets that criteria, even if the impact is disparate.

But if they use an IQ test, suddenly there's a slippery slope: Why is the cutoff 130? The error range on IQ tests is non-zero, so what if a black candidate with 129 comes in? How do you defend that disparate impact in court? You can't.