ABSTRACT Police officers play a key role in determining the result of incidents that involve people in mental health crisis given their role as first responders and gatekeepers to services. In this paper, we ethnographically study one Canadian, mid-size municipal police service’s integration of an electronic mental health screener (MHS). The screener was designed to assist officers in undertaking risk assessment, as well as facilitate collaborative action between police and emergency department staff by providing a tool that uses a shared medical language. Drawing on the theoretical concepts of ‘boundary objects’ and ‘technological frames’, we explore: (1) how the technology worked in practice and, what, if any, perceived impact it had on police decision-making; and, (2) how the technology was perceived to affect information sharing and collaboration among the criminal justice and health systems, and subsequently, the outcome of mental health calls for service. From our analysis, we argue that frontline officers and police administration hold differing, and at times, incongruent technological frames towards MHS. Specifically, we argue that frontline officers do not perceive the screener as providing a shared understanding that facilitates risk assessment, but instead perceive it to be a performance management tool used to track officer decision-making, enable the collection and sharing of health information within the criminal justice system, and demonstrate accountability to police service boards. Further, our analysis illuminates the power of experiential knowledge in resisting technological adoption and organisational reform.