Doesn’t just occur in criminal justice, apparently. The civil side sees it, too, according to this new study tipped by Empirical Legal Studies:
Applying matching methods to sex discrimination suits resolved in the federal circuits between 1995 and 2002 yields two clear results. First, we observe substantial individual effects: The likelihood of a judge deciding in favor of the party alleging discrimination decreases by about 10 percentage points when the judge is a male. Likewise, we find that men are significantly more likely to rule in favor of the rights litigant when a woman serves on the panel. Both effects are so persistent and consistent that they may come as a surprise even to those scholars who have long posited the existence of gendered judging.
So, it looks like any conclusions of future sentencing disparity studies might have to consider more than the factors involved in our cj system.