Research on medical interactions shows how the discursive construction of the clinical case impacts diagnostic reasoning and treatment recommendations. Drawing on an ethnographic study in an intensive care unit, we illustrate how this process is at play in a ward that adopts an extreme, guideline-divergent policy as to the use of antibiotics. The article focuses on how physicians assemble the case as ‘treatable’ or ‘not yet treatable’, and how in doing so they ‘talk into being’ two contrastive policies on antibiotics (...) and position themselves toward the one adopted in the ward. The analysis identifies the discursive resources displayed by physicians to both project an infectious disease diagnosis and resist this treatment-implicative trajectory. We argue that the physicians’ contentious discursive construction of the case has crucial consequences in the way the ward’s extreme policy is jointly accomplished as a highly reflexive process sensitive to the contingencies of any particular case. (shrink)