UPDATE (June 23, 11 a.m.): On Thursday morning, the Supreme Court voted 4-3 to uphold the affirmative action program of the University of Texas at Austin. The program considers race as one factor in admitting some students to the university’s freshman class. “Considerable deference is owed to a university in defining those intangible characteristics, like student body diversity, that are central to its identity and educational mission,” the court said in its majority opinion, which was written by Justice Anthony Kennedy. This article, which was first published on Dec. 9, 2015, explains the background of the case.

Affirmative action in higher education is back in the Supreme Court, with oral arguments in Fisher v. University of Texas at Austin being heard Wednesday. The topic has been contentious in Texas, where a federal appeals court banned affirmative action at the state’s flagship universities in 1996, a move that was then reversed by a Supreme Court decision in 2003. This specific case, which was originally heard by the Supreme Court in 2012 and sent back to the lower court for further review, will once again determine whether UT can consider race as an admissions factor.

The court is expected to reverse the Fifth Circuit’s decision that backed UT’s policy, a move that could affect other schools and decrease diversity at large public colleges.

Affirmative action policies, which encourage universities to use an applicant’s race as an admissions factor in order to increase racial diversity on campus, were never meant to be permanent. In the 2003 Grutter v. Bollinger decision, which upheld affirmative action at the University of Michigan Law School, Justice Sandra Day O’Connor wrote, “The Court expects that 25 years from now, the use of racial preferences will no longer be necessary to further the interest approved today.” But that decision was only 12 years ago, and the data suggests that we’re still a long way from having proportional minority representation on large public college campuses.

We can get a glimpse of how these policies affect student bodies by comparing public college enrollment rates among demographic groups in the eight states where affirmative action is banned to the states where it is not. The most recent data available from the U.S. Department of Education and the Census Bureau shows that white students are slightly underrepresented at a majority of public research universities, typically the campuses where affirmative action is under fire, and Asian students are overrepresented at a majority of these campuses. Black and Hispanic students are still vastly underrepresented at these colleges overall, and they fare even worse in states with bans on affirmative action. Black students are underrepresented by at least 20 percent at 79 percent of the country’s research universities; only two research universities in states with affirmative action bans have at least the same proportion of black students as the state’s college-age population, and one of those, Florida A&M University, is a historically black college or university (HBCU).

Hispanic students are underrepresented by at least 20 percent at 82 percent of the country’s public research universities. In states with affirmative action bans, only one school, Florida International University, has at least the same proportion of Hispanic students as the state’s college-age population.

Minorities found more representation on college campuses when affirmative action policies were in place. As The New York Times has pointed out, in most states that have banned affirmative action, the gap between the proportion of minority representation on these campuses and the proportion of minorities in states’ college-age populations has grown since the bans took effect.

A 2013 University of Washington study found that minority students have a harder time getting accepted to public research universities in states that have banned affirmative action. Researchers looked at the effect race had on admissions and saw a 23 percentage point drop in the chance of admission for minority students in states with bans, compared with a 1 percentage point drop in other states, relative to nonminority students.

Opponents of affirmative action argue that aiming for diversity in areas other than race, such as socioeconomic class, can ensure sufficiently diverse student bodies. The most common race-neutral policy used as an alternative to affirmative action is a plan that the University of Texas already uses, in which a percentage of graduates from every high school get automatic admission. These policies have been shown to increase racial and ethnic diversity on campus, but research on whether they’re as effective as more explicit race-based affirmative action policies has been mixed, and critics say that it doesn’t make sense to use a proxy when so many colleges continue to struggle with racial diversity.

Whether the justices will focus more narrowly on UT’s policy or more broadly on affirmative action in oral arguments is anyone’s guess. But in the midst of a larger conversation about racial diversity on college campuses, it’s hard to ignore the potential impact that this case could have.

CORRECTION (Dec. 9, 11:45 a.m.): An earlier version of this story incorrectly described the decision to halt affirmative action plans in Texas in 1996. The state did not ban affirmative action in 1996; the U.S. Court of Appeals for the Fifth Circuit that year banned the use of race as a factor in admissions to the University of Texas Law School, a decision that had the broader effect of limiting affirmative action statewide but was reversed by the Supreme Court in 2003.

Read more:

Mizzou’s Racial Gap Is Typical On College Campuses

Here Are The Demands From Students Protesting Racism At 51 Colleges