Competing Models of Judicial Coalition Formation and Case Outcome Determination

Abstract

Forming a coalition on a multi-judge panel involves an inherent trade-off between coalition maximization and ideological outcome optimization. Much scholarship is premised on assumptions about how judges make that trade-off; these assumptions have consequences for how we view and measure judicial decision-making. Specifying these assumptions, formally modeling their effects, and basing measures of judicial behavior on these results offer the potential to improve analysis of judicial decision-making.This article formally explores three commonly posited modes of judicial decision-making: a minimum winning coalition model, representing attitudinalist views of judicial decision-making; a maximum winning coalition, capturing the effect of norms of joint opinion writing and collegiality; and a strategic model, incorporating the concept of the credibility of a marginal justice's threat to defect from a majority coalition. Each model yields comprehensive predictions of case outcome positions and coalition sizes under given Court compositions; the Rehnquist Court and Roberts Courts are examined here. The models are then operationalized as measures for empirical use. The different impact of the three measures is illustrated by re-running Baird and Jacobi's analysis of judicial signaling on case outcomes using each measure.

Judicial Choice among Cases for Certiorari

“…into majority opinion outcomes (see Jacobi 2009), and we do not replicate that here. For simplicity, we restrict our analysis to the choice between two sets of cases, from which one case dominates each set, thus the choice is between two cases.…”

Strategic Defiance and Compliance in the U.S. Courts of Appeals

“…If the median member of the Court always controls the final outcome, these two coalitions will produce identical opinions, assuming that Kennedy is the median justice. Nonetheless, how to measure the location of the Court's opinions remains an unanswered question in the literature (see Bonneau et al 2007; Jacobi 2009; Lax and Cameron 2007). As a result, we also used the Court median as a measure of the Court's output.…”

Ideology and the Study of Judicial Behavior

“…Computer programs such as Wordscore can assist in measuring these differences (McGuire & Vanberg, 2005). Alternatively, we could assign the opinion the Martin-Quinn score of the median member of the majority (Jacobi, 2009). Another possibility would be to focus on the ideology of the majority opinion writer.…”