This article deals with discretionary decisions made by British immigration officers about whether to detain asylum seekers. It takes as its point of departure the remarkable variety of views and practices reported by front line decision-makers interviewed at British ports (Weber and Gelsthorpe 2000; Weber and Landman 2002). The discussion begins by drawing historical parallels between the pre-Holocaust era and the present day hostility towards asylum seekers, which forms the wider context for official decision-making. It notes the failure of structural analyses to account for individual differences in rule-following and draws on theoretical perspectives developed by American social psychologists Kelman and Hamilton (1989) to explore the individual dynamics of conformity and dissent. In the concluding section, theoretical connections are made between the idea of discretionary detention as a crime of obedience, and contemporary discussion about state crime and governmentality. The underlying message of this article is as much a normative as an analytical one. While recognizing the practical limitations of individual conscience, the discussion ends, as it begins, by celebrating the emancipatory potential of dissent in the face of populist policies that sanction harm against targeted groups.