Richard Sander writes a Pope Center commentary on the U.S. Supreme Court’s consideration of the controversial Fisher v. Texas case.

Affirmative action is before the Supreme Court again this week, as it rehears arguments in Fisher v. University of Texas. …

But perhaps the most important question about racial preferences is one that’s not directly raised by the case: do they even work? Do they help underrepresented minorities to achieve their goals, and foster interracial interaction and understanding on elite campuses? Or do large preferences often “mismatch” students in campuses where they will struggle and fail?

Scholars began empirically studying the mismatch issue in the 1990s, but in the past five years the field has matured. There are now dozens of careful, peer-reviewed studies that find strong evidence of mismatch. None of the authors of these studies claim that mismatch is a universal or inevitable consequence of affirmative action. But in my view, only demagogues (of which there is, unfortunately, no shortage) or people who haven’t read the relevant literature can still claim that mismatch is not a genuine problem.

It is helpful to think about mismatch as three interrelated phenomena that could affect a student of any race—let’s call her Sally—who receives a large admissions preference, so that she attends a college where her level of academic preparation is substantially below that of her peers.

First, “learning mismatch” occurs if Sally learns less than she would at a less competitive school, because the pace is too fast or her professors are pitching their material at a level that’s not ideal for her. Others and I have argued that learning mismatch occurs on a massive scale in American law schools, where African-Americans (and some other students) tend to receive very large preferences and then, very often, are never able to practice law because they cannot pass bar exams.

Our best estimate is that only about one-third of blacks who start law school in America successfully graduate and pass the bar exam on their first attempt. …

A second form of mismatch—“competition” mismatch—occurs when students abandon particular fields, or college itself, because of the practical and psychological effects of competing with better-prepared students.