You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Affirmative_action_in_the_United_States

Context:
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 Opponents of affirmative action argue that these policies are outdated and lead to reverse discrimination which entails favoring one group over another based upon racial preference rather than achievement.

Question:
What case determined that some implementation of affirmative action was unconstitutional?

Gratz v. Bollinger