Managerialism is omnipresent in Western criminal justice systems, most evident through an emphasis on efficiency, effectiveness, and value-formoney. However, closer examination of components of criminal justice systems can reveal complexities for managerial ideologies in policy and practice. Drawn from an empirical analysis of political debates, policy documents and interviews with stakeholder groups, this article deconstructs the complex role of managerialism in Irish DNA database policy and practice. Despite the appeal of DNA databases to managerial values, this analysis reveals that complexities and tensions in the application of managerialist principles to database policy and practice remain. Notably, although central components of managerialism were promoted, there were significant and unanticipated challenges during the implementation stage of the Irish DNA database. This is evident through three key findings. First, there were differing emphases on ‘efficiency’ and how efficiency manifests in practice. Second, a disjuncture between resource commitments for the database and the reality in practice was identified. Finally, a tension between independence and systemisation in the case of policing and forensic sectors emerged. Taken collectively, this empirical account illustrates the value of real-world case studies and contributes to criminal justice scholarship on both managerialism and the implementation of DNA policy.