Observation of professional relations in a work collective, performed as part of our research work on stress in the police force, led us to question the way the job of police officer is configured in emergency police squads. Adopting an ergonomic approach, we looked at the causes of stress in the way work is organised as this can lead to prescription-related imperfections compared with the needs of both users and professionals. Faced with deep-reaching changes in public policy and socially-evolving populations, police officers’ work is characterised by critical situations in terms of service relations, which can cause tension. Looked at in this way, stressful situations need to be questioned in relation to the conditions in which the professional activity is performed, i.e. with respect to the individual and collective regulations implemented in order to manage conflicts (in relation to objectives) and the difficulties caused by the tasks themselves. This appears to be preferable to examining stressful situations in relation to the individual fragility of police officers when having to manage violent situations. Indeed, the work collective, together with the team leader, can act as a resource that contributes to activity performance and the preservation of everybody’s health.