In the Fisherv. Texas case where a white woman was denied admission to the law school at the University of Texas, the majority on the United States Supreme Court held,

This plan was totally unacceptable since it was NOT based on a multitude of practical, realistic factors and but solely on racial imbalance or a quota.

Affirmative action plans that are based on racial classifications will be reviewed very closely under "strict scrutiny" and the Equal Protection Clause but they found that granting minorities admission based on "critical mass" was allowed under this case in $2016.$

Congress had amended the Civil Rights Act of $1964$ to allow the type of affirmative action program set up by the University of Texas.

Diversity fosters, rather than minimizes, the use of race. It treats minorities as a group, rather than as individuals & therefore affirmative action is always legal if based on race.

The Supreme Court of the United States stred all of the above in its majority opinion.