Read this and answer the question. If the question is unanswerable, say "unanswerable".

Affirmative action is a subject of controversy. Some policies adopted as affirmative action, such as racial quotas or gender quotas for collegiate admission, have been criticized as a form of reverse discrimination, and such implementation of affirmative action has been ruled unconstitutional by the majority opinion of Gratz v. Bollinger. Affirmative action as a practice was upheld by the Supreme Court's decision in Grutter v. Bollinger in 2003. Affirmative action policies were developed in order to correct decades of discrimination stemming from the Reconstruction Era by granting disadvantaged minorities opportunities. Many believe that the diversity of current American society suggests that affirmative action policies succeeded and are no longer required. Opponents of affirmative action argue that these policies are outdated and lead to reverse discrimination which entails favoring one group over another based upon racial preference rather than achievement.

What case determined that some implementation of affirmative action was unconstitutional?
Gratz v. Bollinger