The Czech research evaluation policy was rooted in an instrumental paradigm of policy process and evidence embodied in metrics-based cost-benefit logic. But this framework disintegrated when confronted with actual institutional interests. Based on the ethnography of university departments, this study shows how academics challenged the notion of evidence for evaluation. It is argued that research policy should be studied as an arena of conflicting group and individual interests, where policy process is regarded as a contested meaning-making process rather than a rational-technical one. It is demonstrated that the role of evidence in research evaluation policies is situational according to the knowledge regimes of the academic communities involved.