The two together are "the best available predictor" of first-year law performance, and even that isn't accurate.
What currently available predictor should LSAT/GPA be replaced with?
Also, why exactly does AA turn the LSAT/GPA concept on its ear? I would assume (though I'm not certain) that among AA admits, the students who benefit from it are still among the highest LSAT/GPAs of their particular demographic, so its not like LSAT/GPA is irrelevant for URMs. The fact that these students do comparable to non-URMs once in school or in the job market (I'm assuming they do) makes better evidence that the test is racially skewed than that it's ineffective.
Actually, they don't do as well - at least in school. There is a relatively recent study from the University of Michigan that examines this very issue. It focused on AA students at Michigan Law. It found that that white students do get better law school grades, yet there is no measurable difference between the performance/success of AA students and white students post-graduation.
I don't want to, and frankly cannot, argue about what this study really means. I also don't bring it up to nitpick. I just think it's pretty interesting. Malcolm Gladwell has a compelling interpretation in his book, Outliers.
Let's use some LR here. First, a study aimed at LSAT and first-year law performance would be unrepresentative, if done at a small number of schools, or, worse, a single school.
Secondly, the correlation you cite may be the result of self-fulfilling prophecy.
African American and Latino students, for example, are automatically stigmatized upon entry to top law and medical programs. White, Asian and Arab peers view them with suspicion or dismiss them outright as unworthy, which results in marginalization and exclusion from study groups, access to some resources and an overall feeling of separation. This is deleterious for relations between African-American and Latino students with High GPA's and test scores and white students, as well as the lower numbered ethnic students and the rest of the student body. Imagine having to sit in class as your peers looked at you wondering HOW
you managed to gain admission. "Are you one of those 'AA admits' who, in my opinion, 'really shouldn't be here'?" Or are you one of those rare Blacks who "get's it": really does have super high grades and did very well on the LSAT, speaks like we do, walks, acts, dresses, and behaves like I want Blacks to? I don't mind you getting in if you're like that. But my friend applied. He/she didn't get in, and YOU got his/her seat. You probably weren't as qualified; I don't like that. After I graduate, I'm going to work in admissions, so I can prevent this from happening."
Imagine one of your profs wondering the same things, or worse, having voted against
your admission, only to see you sitting in their class, or that of a close colleague the following Autumn. Now imagine that you attend school knowing people are silently questioning your qualifications and those of others like you, and there's absolutely nothing you can do about it, short of getting straight A's - which only 5% of the class will do, regardless of background.
But you raise an important point here. A law school's mission is to turn out good lawyers, not good first year law students. Why use an exam that does NOT serve that purpose? That's what the Berkeley study is trying to fix.
There are also studies showing Blacks leaving BigLaw at a higher clip than do White associates. This, too, is likely the result of self-sulfilling prophecy, where White partners and senior associates, tend to feel more comfortable with those who look like them (read: White males), thus, supply them with access to more resources and materials, groom and coach them meticulously, give them meaty assignments, spend more time with them, teach them the tricks of the trade, grade them less harshly on performance, and nominate them for increases in responsibility, and awards. The fact that those Black associates who leave BigLaw within just a few years tend to do so voluntarily - contrary to the popular belief that the attrition is the fruit of affirmative action collapsing - is very telling.