evidence: In this month’s issue, Professor Neal Katyal and Thomas Schmidt join a distinguished group of lawyers and judges who criticize the "canon of constitutional avoidance" — the idea that courts should try to interpret statutes so as to avoid raising difficult questions of constitutional law.1 Although the Supreme Court has described this canon as a "settled policy,"2 the canon exists more by dint of repetition than by force of argument. Its critics include the most eminent circuit judge of the last generation,3 two of the most eminent circuit judges of the present generation,4 and a host of thoughtful scholars.5 [...] According to Katyal and Schmidt, moreover, the handwaving sometimes ends up having precedential effect in later cases.38 The scope of that problem is not clear. Indeed, Adrian Vermeule has previously made an opposing assertion: "The case law is rife with constitutional questions that the Court has avoided by construction, only later to hold, when forced to confront the question under a different statute, that the constitutional claim should not prevail."39 But Vermeule’s examples are not really apt.40 While we lack systematic research on the horizontal, vertical, and interbranch precedential effects of avoidance decisions, it is possible that the canon about avoiding constitutional questions is bad for constitutional doctrine.