This article addresses the challenge that post-truth politics poses to teaching authority in information literacy. First, it isolates an element of the post-truth phenomenon, an element it calls "post-facts", to elucidate why teaching source evaluation is not, by itself, an antidote to fake news or other evidence of Americans' media illiteracy. Second, it addresses the implications of post-facts politics for the concept of authority as defined by the "Framework for Information Literacy for Higher Education," drawing on the work of Patrick Wilson and Max Weber to illustrate which elements of authority librarians must rethink due to recent events.