This article explores the ethical challenges of conducting fieldwork in state institutions. It critically engages with the chain of competing claims and multiple loyalties that confront social researchers, and addresses as the main question: how does working with people with whose goals one fundamentally disagrees shape the necessity of building collaborative alliances and trust?

Drawing on the experience of a sensitive and precarious procedure – the administrative hearing of two fiancés suspected of a sham union – the article aims to give situated answers to general questions about the ethics of fieldwork relations. By challenging ideas about trust, neutrality and loyalty, it explores the tensions between building field alliances and private moral and political alignments. In the light of such dissonance, the article discusses the stakes of disclosure and the imposition of a covert role in forging alliances; the consequences of working in a state institution, where ‘customers’ are submitted to civil servants’ discretionary power; and how this blurs, for the researcher, the opposition between adopting a neutral stance and taking sides. Finally, the article addresses the ethics of unethical alliances and how this tension challenges choices in portraying and betraying research participants.