That’s the bottom line of this fascinating study by Daniel Chen and Arnaud Philippe. The authors looked at more than four million sentencing decisions in France, and another 600,000 in the U.S. federal courts. They found that French sentences are 3% shorter, and U.S. federal sentences are 33% shorter in the day component, when the defendant is celebrating a birthday. (Month components were unaffected.) The authors also found that in the U.S. courts, significant birthday leniency exists only where the defendant and the judge share the same race.
I am always cautious about making too much of one study, but there certainly seems to be some basis for the authors’ conclusion that “social norms transmitted through rituals can perversely lead to unfair or incorrect decisions in important situations even when professional norms have been designed to mute them.”