Genomics-related "deliberative" public consultations are all the rage. Drawing from theories of deliberative democracy, run by social scientists, governments and non-profit organizations globally, these events can produce valuable insights and governance solutions. There is a danger, however, of "deliberation" being viewed by its new practitioners as a homogenous "tool" due to a marked lack of analysis of the discursive processes at play. This paper addresses this gap, employing the discourse theory of Laclau to analyze small and large group deliberation at a public consultation on biobanking in British Columbia (BC), Canada, during 2007. Ethnographic and transcript analysis reveals small group deliberation to be a two-stage process, operating according to two different discursive logics. The paper concludes with five lessons for theorists and practitioners of deliberative public engagement with science.