Why has affirmative action failed in the United States- how to answer this question

Firstly, when answering this question I would define what affirmative action is. This tells the examiner that you have background knowledge of the subject and also works as a good introduction for the question.
For example: series of programmes aimed at promoting equality of opportunity for African-Americans, also known as positive discrimination, can be through racial quotas or using race as a factor amongst many, introduced by JFK 1960s.
The next section is asking you to address the reasons why affirmative actions has failed. For a 15 mark question such as this, you should aim for 4 reasons to demonstrate a breadth of knowledge.
In order to demonstrate this in a coherent way, the best technique would be to do a PEE paragraph:PointEvidenceExplain
Point: One reason why affirmative action has failed is to do with the Supreme Court
Evidence: For example, the Supreme Court has set a precedent that does not favour affirmative action in cases such as Clarence v Thomas and Grutter v Bollinger.
Explain: The fact that the highest legislative body in the United States has entrenched a precedent hostile towards affirmative action means that pushing for this type of legislation is incredibly challenging and that institutionally America is hostile towards this type of action. Thus, affirmative action has inevitably failed due to the Supreme Court posing a strong opposition.
This is typical of a 15 mark question structure and can be applied to many different questions.