The wave of state election legislation in 2021 is the most recent example of a broader pattern described in Terri Jennings Peretti’s Partisan Supremacy. Peretti shows that the modern Republican Party, whose demographic and geographic support has not appreciably broadened in the past generation, has pursued favorable interpretations of election law “to enhance its competitiveness and sustain its power” (p. 205). The United States Supreme Court has consistently supplied these desired interpretations. The book’s central claim is that such rulings are best understood as an essentially partisan form of judicial behavior: the Republican-appointed Court majority has been central to the long-term strategy that has sustained the GOP’s electoral viability.

Making this case requires carefully distinguishing partisanship and judicial ideology—a distinction that research on judicial behavior has mostly effaced. However, Peretti persuasively argues that election law, in which case outcomes may directly shape the fortunes of parties, often creates observable conflict between judges’ legal preferences and underlying party loyalties. Party often comes first. The book describes the evolution of a Republican-friendly body of election law through close examination of the Supreme Court’s work on four matters: the Voting Rights Act (VRA), state voter identification laws, redistricting, and campaign finance regulation.

The analysis begins with the VRA. Peretti argues that Shelby County v. Holder, the 2013 decision that ended federal oversight of jurisdictions with serious histories of voter discrimination, was the outcome of decades of Republican efforts to weaken the VRA. In Congress, Republicans often sought to prevent reauthorization or add provisions that would limit the strength and restrict the scope of the VRA’s protections. The Justice Department enforced the VRA less vigorously under Republican presidents. And, for decades, new Supreme Court Justices nominated by Republican presidents offered narrower interpretations of the VRA than predecessors from either party.

The book then turns to voter identification laws. Drawing on the complete body of state and lower federal court opinions about voter identification laws, Peretti shows that Republican judges have consistently ruled in their favor, whereas Democratic judges’ views, although broadly opposed, have been constrained by the Supreme Court’s major ruling on voter identification laws, Crawford v. Marion County Election Board. Peretti aptly notes that partisan conflict on voter identification laws has been sharper than their measurable effects might warrant and is out of step with less-polarized public opinion. The chapter is an excellent illustration of how a muddled, plurality Court opinion may solidify into a strong precedent and is commendable for recognizing Crawford, rather than Shelby County, as a true turning point in twenty-first-century election law.

The discussion of redistricting begins with an account of the Warren Court’s reapportionment revolution. Peretti thoughtfully characterizes this not as a neutral defense of democracy, but as a shift whose late development and particular provisions must be understood in part as a form of judicial support for the Democratic electoral coalition—a useful reminder that election law has always had high partisan stakes. Walking through the Court’s long, difficult line of opinions on redistricting for (nonracialized) partisan advantage, Peretti suggests that consistently polarized judicial voting cannot be neatly linked to Republican strategy. In the long term, gerrymandering has not been a prominent GOP concern, the Republican Party has not maintained a consistent position, and the national party has been highly deferential to state and local actors. In cases about the 2020 US Census form and apportionment on the basis of the citizen voting-age population, where partisan interest and judicial ideology stood in partial conflict, the Roberts Court has taken an ideological line. The Court’s thinking on racial gerrymandering, too, tends to reflect a legal ideology of color blindness rather than partisanship—and, indeed, both major parties hold ever-evolving views on racial considerations in districting.

The empirical account concludes with the Court’s rulings on campaign finance, where Peretti shows that judicial voting is extraordinarily polarized, but partisan and ideological matters can only be partly disentangled. The Roberts Court’s rulings on campaign finance and public sector unions are mostly concordant with its reasoning about a range of less obviously partisan free speech matters. Nor is it clear how these rulings will affect the vitality of public sector unions or whether weakened campaign finance regulations favor Republicans. Although its findings incompletely support the book’s thesis, the chapter offers an impressively clear-sighted account of a singularly complex body of law.

Peretti is ever attentive to legal detail and the intellectual tendencies of specific justices. The conclusion acknowledges that such evidence sometimes fits awkwardly with the book’s regime politics theory, an account that is national in its scope and generational in its timescale. A meso-level account of legal mobilization—or a view of political advantage seeking on a shorter timescale or at the state and local level—would enrich parts of the discussion. The book seeks to demonstrate that the Republican Party “caused” cases to be generated and decided in its own favor. This is a simple but plausible characterization of suits about the VRA and campaign finance, where actors in the Republican Party initiated and sustained complex legal mobilizations. Regarding gerrymandering or voter identification laws, however, Republican officials took actions that were challenged by others. Rather than seeking doctrinal shifts, defenders of those practices—generally state officials—have sought to keep them out of the federal courtroom and have almost invariably offered arguments that sought to conclude cases without reaching a decision on the merits. At times, then, case law has shifted in Republicans’ favor despite the legal strategies of Republican officials. The slippage is important, because it raises questions of strategy and foresight. It is not always clear that the practical results of decisions were foreseeable. Opportunism, legal experiment, and intellectual uncertainty, as well as predefined strategy, have a place in understanding the development of election law.

These concerns, however, may have more to do with broader theory than Peretti’s specific contribution. There is much to like about Partisan Supremacy. The book’s distinction between legal ideology and party loyalty emphasizes not simply that judges are political figures, but also that they are political in various ways. The distinction might be especially productive in studying state courts, which are often connected more closely to party politics than the federal judiciary and deal with many narrow election law questions that have obvious practical stakes. Owing in part to the doctrinal shifts Peretti chronicles, state courts will also become a more important forum for voting rights claims in the coming years.

The book is a model of expository and investigative clarity. The account of legal issues and their political effects unfolds with an ease rarely found in either legal or social scientific scholarship; such direct, assured handling of both cases and prior research can arise only from an author’s deep understanding. The book is also unusually clear in stating research questions, making predictions, accounting for analytical choices, and acknowledging evidentiary ambiguities and limitations. Partisan Supremacy is both a model for how to study this unsettled moment in election law and an invaluable introduction for readers who wish to know how this important law assumed its current form.