Imagine that you are the judge asked to sentence a convict named Shon Hopwood, a twenty-three-year-old Nebraskan who has begged you for leniency and sworn he will change his ways. Hopwood has made a full and honest confession of all his crimes and can point to two years of service in the Navy, his past as a basketball star in high school, and a seemingly earnest repentance and desire to change. But he has also robbed five banks, brandishing a gun, and spent the proceeds on alcohol and drugs.

Sentencing decisions change lives forever, and, for that reason and others, they’re hard to make. It is often suspected that different judges sentence differently, and we now have a better idea of this. A giant, forthcoming study of the federal judiciary reveals clear patterns: Democrats and women are slightly more lenient. Where you’re sentenced matters even more. Judges in the South are harsher; in the Northeast and on the West Coast, they are more easygoing.

The study’s author is Crystal Yang, a fellow at the University of Chicago Law School, who based it on data from more than six hundred thousand convicted defendants between 2000 and 2009. (Impressively, in certain ways her study exceeds the work of the United States Sentencing Commission.) She writes, “Female judges sentenced observably similar defendants to approximately 1.7 months less than their male colleagues.” In addition, judges appointed by a Democratic President were 2.2 per cent more likely to exercise leniency. Regional effects are more challenging to measure, because, for example, the kinds of crime that happen in New York might differ from those in Texas. But recent data suggest that, controlling for cases and defendant types, “there is substantial variation in the sentence that a defendant would receive depending on the district court in which he is sentenced”—as much as eleven months, on average. The results are all statistically significant, according to Yang—and, if the differences sound relatively small, it is also important to remember that what she is measuring are average differences. In straightforward cases, judges may be more likely to issue similar rulings. It’s the hard cases where judges vary. In a case on the edge, the identity of your judge might make an important difference.

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