After the University of Michigan's use of affirmative action was upheld by the Supreme Court in 2003, voters approved a constitutional ban. The 6-2 ruling here doesn't really address affirmative action but rather the voter's right to address it.
Opponents of the ban seem to argue that a decline in minority enrollment shows that banning affirmative action leads to discrimination. A more compelling argument can be made it's prove that discrimination was happening under affirmative action. If banning using race in admission decisions has led to a decline in minority enrollment, can't you easily make the argument that students that would't have otherwise qualified for the U of M were accepted because of their race or ethnicity?
How is ending an advantage based purely on skin color discrimination?