Scientific uncertainty is inevitable in many public policy debates, especially in the environmental and public health arena. Scientists, lawyers, and media professionals develop and communicate the data, information, and analysis that inform public decisionmaking. But each of these professions regards and communicates scientific uncertainty differently, in part due to varying professional norms and ethical standards. On September 12, 2014, the Environmental Law Institute hosted a webinar to examine how the fields of science, law, and journalism each address scientific uncertainty, and how core professional norms shape the way they communicate it. Here, we present a transcript of the event, which has been edited for style, clarity, and space considerations.