Abstract: Conviction rates in Japan exceed 99 percent. Because Japanese judges can be penalized by a personnel office if they rule in ways the office dislikes, perhaps they face biased incentives to convict. Using data on the careers and opinions of 321 Japanese judges, we find that judges who acquit do have worse careers following the acquittal. On closer examination, though, we find that the punished judges are not those who acquit on the ground that the prosecutors charged the wrong person. Rather, they acquit for reasons of statutory or constitutional interpretation, often in politically charged cases. Thus, the apparent punishment seems unrelated to any pro‐conviction bias at the judicial administrative offices. We suggest an alternative explanation: the high conviction rates reflect case selection and low prosecutorial budgets; understaffed prosecutors present judges with only the most obviously guilty defendants.