When Food and Drug Commissioner Scott Gottlieb threatened to crack down on vaping products last month in response to "an epidemic of e-cigarette use among teenagers," he alluded to "preliminary data" showing that "youth use of e-cigs is rising very sharply." Although we still have not seen those numbers, that has not stopped Gottlieb from making policy decisions based on them, including changes that could limit the appeal and availability of products he concedes have enormous potential to reduce the harm caused by smoking.