BYU Law Review


Judges shape the law with their votes and the reasoning in their opinions. An important element of the latter is which opinions they follow, and thus elevate, and which they cast doubt on, and thus diminish. Using a unique and comprehensive dataset containing the substantive Shepard’s treatments of all circuit court published and unpublished majority opinions issued between 1974 and 2017, we examine the relationship between judges’ substantive treatments of earlier appellate cases and their party, race, and gender. Are judges more likely to follow opinions written by colleagues of the same party, race, or gender? What we find is both surprising and nuanced. We have two major findings. First, over the forty-four-year span we studied, we find growing partisan differences in positive treatments of earlier cases. The partisan differences are largest for treatments in ideologically salient categories of cases. Interestingly, the partisan differences arise more for treatments of opinions written by Democratic appointees than for opinions written by Republican appointees, which we think is best explained by an accelerating movement among Republican appointees in a conservative direction compared to a steady move among Democratic appointees in a liberal direction. The increase in partisan differences is not a function of presidential cohorts or age cohorts. Second, there are intraparty racial and gender differences in positive treatments of past cases, and these differences are similar to the partisan differences. Within each party, Black and White judges differ in their treatments of opinions authored by Black co-partisans, Hispanic and White judges differ in their treatments of opinions authored by Hispanic co-partisans, and female and male judges differ in their treatments of opinions authored by female co-partisans. Similar to the partisan divergence noted above, we also find that some of these differences increase in magnitude over time — with particularly notable increases in the Black-White Democratic differences, Hispanic-White Republican differences, and female-male Republican differences. Notably, the racial and gender differences we find in positive Shepard’s treatments are not mirrored in most studies of racial and gender differences in judicial behavior, which focus on merits votes and include a much smaller number of cases.

These results defy easy explanation. They do not support the proposition that party, race, and gender have always played a pervasive role for judges. Instead, our results provide evidence of increasing partisan, racial, and gender polarization among judges in recent years. For reasons we explain in the body of this Article, the partisan, racial, and gender differences we find appear to be a function of political ideology. Further, because the racial and gender differences are within parties, our results indicate that not only partisan differences but also intraparty racial and gender ideological differences have risen in recent years (particularly for Republican judges).

Our data thus reveal polarization among circuit judges and, as a result, in their shaping of the law. Many groups in the United States have become more ideologically polarized in recent years. Our data indicate that judges are one of them.


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