California’s 1996 constitutional amendment that prohibits public institutions from preferentially discriminating by race, sex, and ethnicity may be reversed later this year to restore explicit affirmative-action policies.

Some social-justice groups and state legislators argue that opportunities, incomes, and college admissions of people of color and women are significantly depressed by significant racial, ethnic, and gender biases. According to these groups, the road to equal opportunity for women and people of color is giving job and college admission preferences to them to offset the racism and biases that these groups face.

But claims that these preferences are needed to give people of color and women a fair shot is not supported by a substantial body of research studying the effects of race and sex-based preferential treatment. In fact, several studies indicate that protected groups may have significantly worse outcomes with these preferences than without.

The impact of Proposition 209 on minority student academic performance and graduation rates appears to be positive and substantial. Professor Gail Heriot studied student performance at UC San Diego and found immediate improvement among underrepresented groups. Immediately before the implementation of Proposition 209, only one black student in a first-year class of more than 3,000 students had a GPA of 3.5 or higher, compared to 20 percent of the white students in the first-year class. But the following year, 20 percent of black students had a 3.5 GPA or better after their first year, comparable with whites.

Moreover, 15 percent of black students and 17 percent of Native American students had GPA less than 2.0 before Prop 209, compared to 4 percent of white students. Immediately after Proposition 209’s implementation, this record changed substantially, with the black and native American rates falling to just 6 percent, nearly the same as whites.

More broadly, The University of California reported that underrepresented minority four-year graduation rates rose from about 31 percent just before Prop 209 to 55 percent by 2014.

Moreover, six-year graduation rates for underrepresented minorities has increased to about 75 percent. Admission rates also rose significantly for all underrepresented minorities except African Americans, which stayed about the same. Hispanic student enrollment rates increased from 15 percent to 23 percent, and the rate for Asian Americans increased from 28 percent to 37 percent. The UC student body is by far the most diverse in its history.

A study by four Duke economists shows that after Prop 209, minority graduation rates in California increased, reflecting in part better matching between students and colleges. Matching is the idea that a student will flourish at a college that is the right fit for the person but may have a very difficult time at a college that is not a good fit for them.

For example, suppose that under ethnic admission preferences UC Berkeley aggressively recruits a Latino student, but that the student discovers that UC Berkeley is not the right fit, and then drops out. Without Prop 209, what has happened is that this hypothetical student may have a lower chance of admission at Berkeley and ends up choosing a different college in the UC system that ultimately will be a better match or them.

As Professor Heriot, a member of the US Civil Rights Commission describes, there are many gifted minority students, but not enough to fill the nearly insatiable demands for race and ethnic diversity by colleges. With racial and ethnic preferences, colleges race against one another to see who can assemble the most racially and ethnically diverse first-year class, and the students who fall through the cracks are ultimately the ones who are hurt.

I personally have seen the enormous harm that can be done to a struggling minority student who is not at the right college. I began my teaching career at the University of Pennsylvania. While there, an African American student came to see me, explaining that she was really struggling with her schoolwork and apologizing for her failing grade in my class.

We spoke for quite a long time. She was very bright and creative but had gone to a poorly performing high school where she learned far less than her student peers at Penn. She was extremely depressed, and I helped her connect with student counseling.

She ended up leaving Penn, but we kept in touch afterwards. She enrolled in a junior college to learn what she needed, and ultimately graduated from the University of Maryland. I was delighted to see her succeed, but at the same time, it is sad to think of the many students like her who do not.

The study also found that colleges have done a much better job since passage of Prop 209 in supporting these students should they face academic or other challenges.

There is an important inconsistency regarding the argument of those desiring to restore race-based preferences. Students of Asian descent are much more represented in the UC system, compared with their population share, since Proposition 209. And in terms of gender bias, women now represent nearly 59 percent of the UC student body. This suggests that doing away with Proposition 209 is not about bias and bigotry per se. Instead, the argument is simply used to justify preferential treatment of certain groups.

What is the solution? An incredibly important issue that many California legislators refuse to discuss is the deficient performance of California K–12 education. California ranks 40th for educational quality among US states.

And this is just a relative ranking. Compared to those around the world, US outcomes are roughly in the middle of the pack of peer countries and, in some years, below average and trailing those of much poorer countries. In math achievement, even the highest-performing US states significantly trail the countries with the leading education systems.

More striking is that within California, students from low-income families typically attend the worst-performing public schools. It has been estimated that only about 5 percent of African American students are attending high-performing schools, while whites and those of Asian descent are much more likely to attend a high-performing school.

Creating a high-performing school system is a key part of the foundation toward building a society where all have the knowledge base and skills to succeed. Year after year, California school performance remains far below acceptable, despite substantial budget increases. The bulk of peer-reviewed research shows that this deficiency is significantly related to policy.

This body of research concludes that implementing common-sense reforms to the rules governing tenure and promotion, to pay criteria, and to the high costs of firing a poorly performing teacher would substantially raise student performance. These reforms have become so obviously needed that they are constantly advanced within policy circles, but they ultimately are suppressed by teacher unions, which in turn have a very close political relationship with many California lawmakers.

California state senator Ling Ling Chang (R-Diamond Bar) recently remarked, “Our academic admission process should be fair and even for all who apply. Having institutions of higher learning pick winners and losers based on nothing more than race is an abhorrent practice and something that should not be allowed ever in this country.”

Senator Chang’s statement should be heeded. The evidence indicates that implementing racial and gender preferences may significantly harm the very groups targeted to benefit from this policy. There are common-sense education reforms that will do so much more than race-based preferential policies.

But these education reforms are blocked by the legislators who ironically claim to be the strongest representatives of these targeted groups. Meanwhile, another generation of students from poor households will receive a deficient K–12 education and will face adulthood with far fewer opportunities than they could—and should—have.