In an unexpected affirmation of the Voting Rights Act, the Supreme Court ruled this month that congressional voting maps in Alabama would dilute the power of Black voters.

University of Michigan political science professor Jowei Chen, affiliated with the Center for Political Studies at the Institute for Social Research, was cited throughout the Supreme Court’s Alabama opinion. His work with Harvard Law’s Nicholas Stephanopolous—an amicus brief submitted in the case and their Yale Law Journal article on “The Race-Blind Future of Voting Rights”—provided a critical evidence base for the decision.

The decision in Allen v. Milligan (PDF) specifically affirmed the existing approach to Section 2 litigation that allows race to be considered in determining whether a districting plan discriminates against minority voters.

In the case from Alabama, where Black voters account for 27% of the population but figured as the majority in just one of seven districts on the state’s new congressional map, voting rights advocates had feared the Supreme Court would accept Alabama’s proposed “race-blind” benchmark and undermine the Voting Rights Act of 1965.

Instead, Chief Justice John Roberts’ majority opinion in the 5-to-4 ruling upholds Section 2 and requires that Alabama create a second House district in which Black voters will have the opportunity to elect representatives of their choice.

Chen and Stephanopolous’ amicus brief made three key points: First, it showed that Black and Hispanic voters are disproportionately underrepresented in the vast majority of U.S. states. Second, when minority voters challenge districting plans under Section 2 of the Voting Rights Act, these plaintiffs lose in federal court most of the time. Third, adopting Alabama’s “race-blind” benchmark would likely further reduce the number of majority-Black and majority-Hispanic districts in state legislative plans.

This third point was based on their research that was first to explore the implications of the proposed “race-blind” benchmark. This was a central question in the SCOTUS case: Whether proportionality should be calculated according to minority voters’ representation relative to their share of the population, or by a newly proposed comparator—the fraction of seats they would control if districts were drawn randomly and without the use of racial data. Specifically, Alabama argued that if most computer-simulated districting plans produced using a “race-blind” map-drawing process did not contain two Black voting districts, then its congressional map should not be struck down for failing to contain two Black districts.

Chen and Stephanopolous conducted computer simulations of the redistricting process in 19 states—the states with significant minority populations where the benchmark would have the biggest impact—to analyze how such a “race-blind” benchmark might affect minority representation in the election of legislators. They did so using a technique—the random generation of district maps by a computer algorithm—that the authors noted has become the gold standard in partisan-gerrymandering cases. They did, in other words, exactly what Alabama proposed—to use a computer algorithm to produce millions of race-blind statehouse maps.

The authors found that, compared to the current race conscious approach to Section 2 litigation, a future “race-blind” benchmark in redistricting “would yield substantially fewer districts where minority voters are able to elect their preferred candidates.” In other words, a “race-blind” benchmark would significantly harm minority representation. In most cases, they found minority representation dropped sharply; in Alabama, for example, the number of Black “opportunity districts” (where minority voters can elect their preferred candidates) fell from 27 to a median of 23, falling as low as 18 in the simulations.

Stephanopolous publicly called the decision “an absolutely stunning development,” and Evan Milligan, one of the original plaintiffs in the case, called the ruling a “win for democracy and freedom not just in Alabama but across the United States.”

Following on the Alabama decision, the Supreme Court dismissed an appeal from Louisiana’s seeking to prevent the state’s congressional map from being redrawn over claims that it unlawfully dilutes the influence of Black voters. The move to dismiss the Louisiana case, by way of a brief, unsigned and uncontested order, was expected after the Alabama ruling.

Speaking New York Times columnist Thomas Edsall, Stephanopolous summarized the legal significance of the case last week: “First, it means that Section 2 remains fully operative as a bulwark against racial vote dilution; second, it signals to conservative lower courts that they need to rule in favor of plaintiffs on facts like those in Milligan; third, it takes off the table arguments that Section 2 must be narrowly construed to avoid constitutional problems; and fourth, if Section 2 is constitutional, so should be other laws targeting racial disparities.”

Edsall noted that the decision could result in the replacement of up to five majority-white Republican districts with majority-minority Democratic districts in 2024 House races. In the same column, Michigan Law Professor Ellen Katz highlighted the longer-term uncertainty of the future of the Voting Rights Act, noting that Kavanaugh pointedly left room to shift to a more conservative interpretation in future cases.

Chen studies redistricting, political geography, distributive politics and executive agencies. His research has examined the partisan and racial effects of redistricting maps and the effect of political geography on redistricting outcomes.

In 2019, Common Cause honored Chen as a “Defender of Democracy” for his work on partisan gerrymandering. Unpacking the results of the 2022 midterm elections, Chen presented in the ISR Insights Series last year, observing that redistricting had a major impact on congressional outcomes in Michigan and elsewhere—but that in aggregate, redistricting did not translate to an advantage for either party.