First off, we have just received a interesting ruling on Affirmative action, not going against it but sending it to the lower courts under a tighter standard.
A little more on this.
The standard for any discrimination based on race, including affirmative action, is in the parts;
1) It must achieve a legitimate (state) interest.
In this case this is campus diversity. It's pretty solidly established that diversity is a legitimate interest for colleges (including state colleges) by improving educational and other outcomes for both minority
and majority students. So colleges may discriminate based on race to increase diversity, so long as the program also meets the other two goals.
2) It must be narrowly tailored.
Just having a legitimate reason to discriminate doesn't mean you can discriminate as you wish. Any discrimination must be designed to achieve the specific goal stated and no more.
3) It must be the least restrictive means of achieving the goal.
In this case restrictive means discriminatory. If there was a race neutral method of increasing racial diversity that was shown to work then racial discrimination would automatically be illegal, because it is no longer the least restrictive means of achieving that goal.
In
Fisher it's points 2 and 3 that are combined in the challenge. Essentially the lower court is being asked to check more closely whether the discrimination in admissions policies is actually the absolute minimum racial discrimination required to achieve the diversity goals.
The serious argument here is based on the Texas Top 10% Rule, where the top ten percent of graduates from any given Texas high school are given automatic admission into any Texan public university. This is a (supposedly) race neutral program that is nevertheless designed to give racial and background diversity (based on the racial and background diversity of Texas high schools) to the state universities. It seems a toss up to me whether the lower courts will accept that this program is a non-discriminatory way of achieving racial diversity.