Abstract Approaches combining social and political theory with ontology have rarely been utilised in the evaluation of decision‐making processes. Drawing on such an approach clarifies the questions that still need to be asked about the policy response to HIV / AIDS in The Netherlands in the early 1980s. The initial response in The Netherlands is internationally regarded as an example of successful cooperation between public authorities, health organisations, blood banks and the gay movement. In comparison with other countries, deeply dividing social conflicts as well as dramatic medical disasters were avoided. This image, however, is misleading. Although it was on a smaller scale than the disasters with contaminated blood products in other countries, The Netherlands had their blood scandal too. A reconstruction of this episode offers the opportunity to evaluate the role objects are granted in theories of institutionalisation and to critically examine the procedural notion of politics in actor network theory. The aim of the article is to show that analyses of decision‐making processes under conditions of uncertainty ought to engage more carefully with processes of exclusion and the transformative role of objects.