Systematic reviews in policing have become an increasingly common way for researchers to synthesize the state of research on programs, practices, and policies. Reviews utilize comprehensive and transparent search strategies to identify and summarize the evidence base for a particular topic, providing rigorous assessments of the state of scientific knowledge about policing strategies needed for evidence-based policing. This chapter summarizes findings and conclusions from systematic reviews on policing, building on an earlier paper that included 17 policing reviews completed between 2004 and 2015. In the current chapter, we identify updates to five of these reviews, and new reviews on 13 policing topics. Our “review of reviews” on 30 policing topics suggests a growth in primary research in policing, and in particular an increase in reviews on non-crime control topics. But we also suggest existing reviews provide insufficient “how to” guidance for implementing evidence-based strategies. We argue in concluding that scholars have succeeded in providing a “first generation” of studies that tell us whether general policing approaches are effective, but a much larger evidence based is needed for a “second generation” of systematic reviews that would provide specific guidance about choosing and implementing evidence-based practices in the field.

Questions of causality are central to evidence-based policing (EBP), and have been occupying policing scholars in numerous areas. Experiments are considered the “gold standard” for determining causality, but they are not without limitations and are not always feasible. The present chapter explores the potential contribution of “subjective causality” to policing research. Subjective causality is a complementary, qualitative approach to establishing causality, in which relationships are examined and causality is determined through the subjective lens of the individual. Such an explicit approach to causality is uncommon in qualitative research in policing, and could assist in overcoming some of the challenges of the field. In this chapter we demonstrate how subjective causality can contribute to policing by focusing on an area where establishing causality is receiving particular attention: the presumed effect of police-provided procedural justice on police legitimacy. We use in-depth interviews with protestors who participated in “Occupy Israel” demonstrations in 2012 to explore how qualitative data can be used to identify the subjective, causal relationships that individuals make in their own minds between procedural jusice and legitimacy. We also discuss the applicability and potential contribution of this method to policing research more generally.

Using interview data from protesters and frontline police, this chapter examines the transition of protest policing, from soft to hard models, amid the recent unrest in Hong Kong. While police-centric explanations in the protest policing literature view police as intentional decision-makers who can choose from a variety of policing strategies, we employ a mixed-embeddedness framework that reveals a number of factors—external to police—that have deprived the Hong Kong Police Force of its capacity to facilitate peaceful protest through soft strategies of communication and negotiation. These include, (1) a legitimacy crisis of governance in Hong Kong (a macrolevel factor), (2) the erosion of police authority within the local political culture (a mesolevel factor), and (3) stylistic changes in police–protester interactions, involving the increased use of masks and collective action frames of identification as victims of police (microlevel factors). Together, these factors inaugurated reaction spirals that led to the end of soft, facilitative protest-policing in Hong Kong.