Stephen J. Choi, G. Mitu Gulati, Mirya R. Holman, and Eric A. Posner have a new article up on ssrn, "Judging Women." Here's their abstract:
Judge Sonia Sotomayor’s assertion that female judges might be “better” than male judges has generated accusations of sexism and potential bias. An equally controversial claim is that male judges are better than female judges because the latter have benefited from affirmative action. These claims are susceptible to empirical analysis. Primarily using a dataset of all the state high court judges in 1998-2000, we estimate three measures of judicial output: opinion production, outside state citations, and co-partisan disagreements. We find that the male and female judges perform at about the same level. Roughly similar findings show up in data from the U.S. Court of Appeals and the federal district courts.