Police responses to vulnerable populations: tracking the evolution from “zero-policing” to “co-responding”

Purpose The paper examines the historical shifts in policing strategies towards individuals with SMI and vulnerable populations, highlighting the development of co-response models, introducing the concept of “untethered” co-response. Design/methodology/approach This paper conducts a review of literature to trace the evolution of police responses to individuals with serious mental illness (SMI) and vulnerable populations. It categorizes four generations of police approaches—zero-policing, over-policing, crisis intervention and co-response—and introduces a fifth generation, the “untethered” co-response model exemplified by Project SCOPE in Philadelphia. Findings The review identifies historical patterns of police response to SMI individuals, emphasizing the challenges and consequences associated with over-policing. It outlines the evolution from crisis intervention teams to co-response models and introduces Project SCOPE as an innovative “untethered” co-response approach. Research limitations/implications The research acknowledges the challenges in evaluating the effectiveness of crisis intervention teams and co-response models due to variations in implementation and limited standardized models. It emphasizes the need for more rigorous research, including randomized controlled trials, to substantiate claims about the effectiveness of these models. Practical implications The paper suggests that the “untethered” co-response model, exemplified by Project SCOPE, has the potential to positively impact criminal justice and social service outcomes for vulnerable populations. It encourages ongoing policy and evaluative research to inform evidence-based practice and mitigate collateral harms associated with policing responses. Social implications Given the rising interactions between police and individuals with mental health issues, exacerbated by the COVID-19 pandemic, the paper highlights the urgency for innovative, non-policing-driven responses to vulnerable persons. Originality/value The paper contributes to the literature by proposing a fifth generation of police response to vulnerable persons, the “untethered” co-response model and presenting Project SCOPE as a practical example.