This Article draws on novel data and presents the results of the first empirical analysis of how potentially salient characteristics of Court of Appeals judges influence class certification under Rule 23 of the Federal Rules of Civil Procedure. We find that the ideological composition of the panel (measured by the party of the appointing president) has a very strong association with certification outcomes, with all-Democratic panels having dramatically higher rates of procertification outcomes than all-Republican panels—nearly triple in about the past twenty years. We also find that the presence of one African American on a panel, and the presence of two women (but not one), is associated with procertification outcomes.

Our results show that, contrary to conventional wisdom in scholarship on diversity on the Courts of Appeals, the impact of diversity extends beyond conceptions of “women’s issues” or “minority issues.” The consequences of gender and racial diversity on the bench, through application and elaboration of certification law, radiate widely across the legal landscape, influencing implementation in such areas as consumer, securities, labor and employment, antitrust, insurance, product liability, environmental, and many other areas of law. In considering possible explanations for our findings on the procertification preferences of women and African Americans, we note that class action doctrine, as transsubstantive procedural law, traverses many policy areas. As strategic actors, it would be rational for judges to take into consideration how class-certification doctrine in a case that does not implicate issues on which they have distinctive preferences might affect certification in cases that do. Alternatively, or in addition, our results may be the first evidence that transsubstantive procedural law affecting access to justice is itself a policy domain in which women and African Americans have distinctive preferences. In either case, the results highlight the importance of exploring the effects of diversity on transsubstantive procedural law more generally.

Our findings on gender panel effects in particular are novel in the literature on panel effects and the literature on gender and judging. Past work focusing on substantive antidiscrimination law found that one woman can influence the votes of men in the majority (mirroring what we find with respect to African Americans in class-certification decisions). These results allowed for optimism that the panel structure—which threatens to dilute the influence of underrepresented groups on the bench because they are infrequently in the panel majority—actually facilitates minority influence, whether through deliberation, cue taking, bargaining, or some other mechanism.

Our gender results are quite different and normatively troubling. We observe that women have substantially more procertification preferences based on outcomes when they are in the majority. However, panels with one woman are not more likely to yield procertification outcomes. Panels with women in the majority occur at sharply lower rates than women’s percentage of judgeships, and thus certification doctrine underrepresents their preferences relative to their share of judgeships and overrepresents those of male judges.