平權法案係為矯正美國歷史過去種族歧視之不公，利用積極性手段提供機會與資源，彌補少數族裔或弱勢族群。平權法案之存在理由包含補償、社會正義、種族平等及多樣性因素。其中引起最大爭議為1978年貝基案所奠定的多樣性理論，被視為美國高等教育之重大追求目標的「多樣性」更是法庭過去至今決定平權法案合法性之重要依據。 然而，平權法案歷經超過半世紀實施以來，是否真正帶給需要保障的人權利，以及是否又潛在奪取了誰的權利引起美國各界議論紛紛。反對者質疑多樣性之模糊定義及多樣性與種族的必要連結性；支持者則高舉多樣性學習環境帶來的學習效益與民主效益。 2016年Fisher案以多樣性之教育重大利益再次判定平權法案之合法性，多樣性仍是擁護平權法案存在的重要角色。然而，美國各界看法會持續為影響平權法案合法實施之關鍵，平權法案是否該被廢除的爭議仍會不絕於耳，平權法案的未來走向將繼續受社會、政府與人民三者間之看法與態度左右。 Abstract: “Affirmative action” means to make up for past injustice in U.S. by taking positive steps to provide more resources and chances for especially minorities and the underrepresented. There are four main reasons why affirmative action exists, including remediation, social justice, racial equality, and diversity. The most controversial factor is diversity rationale that was first established in Bakke case(1978). Diversity rationale is seen as a compelling interest in American higher education, and this is what supports the constitutionality of affirmative action from the past cases in Supreme Court. Nonetheless, since affirmative action was executed for more than half of the century, has it provided the right to those who are in need, or violated those who are supposed to be protected? Therefore, affirmative action has been a controversy in U.S. Opponents doubt it because of its ambiguous definition and connectivity with race, while proponents advocate learning environments with diversity, such as the campus or classrooms results in both learning and democratic outcomes. In 2016, the final decision of Fisher case reaffirm the constitutionality of affirmative action because of diversity in learning environments. However, the arguments will continue as long as there are different perceptions among society, governments and people. And this still determines the developments of affirmative action.