The effects of alcohol on witnesses’, victims’, and suspects’ memory pose significant challenges for the criminal justice and legal system. Although seemingly many studies have been carried out over the last 40 years, large research gaps still exist, and the research is yielding somewhat mixed results. The present study used the study space methodology (Malpass et al., 2008; Memon et al., 2010) to synthesize research activities on alcohol’s effects on interviewees’ memory, cognition, and behavior in legal settings, as well as how intoxicated individuals are perceived by legal professionals. The focus was on identifying gaps in important yet understudied areas (i.e., study spaces) within this research field. To this end, we conducted an extensive literature search yielding an initial set of 128 publications. Of these, 90 were relevant and included in this study space analysis. Next, all articles included were categorized into five study space matrices (i.e., nonexperimental perceptions, experimental perceptions, memory for events, memory for faces, and suspect behavior). Each matrix was transformed to a heatmap to graphically show areas with few to many studies. The results are reflected in the heatmaps according to this classification: (a) no-density study space (zero studies), (b) low-density study space (one to nine studies), (c) moderate-density study space (10–19 studies), and (d) high-density study space (≥20 studies). The findings are discussed within the context of developing policy recommendations for gathering best evidence from intoxicated people and to guide future research efforts into areas of importance. (PsycInfo Database Record (c) 2026 APA, all rights reserved

What is it about?

Alcohol-intoxicated witnesses, victims, and suspects are commonly encountered in the legal system. But how much do we really know about how alcohol affects their memory, thinking, and behavior, or how they are perceived by others? In this study, we mapped 40 years of research on alcohol intoxication in legal settings. We reviewed 90 published articles covering areas such as witnesses’ and victims’ memory for events and faces, perceptions of intoxicated individuals, and the behavior of suspects during interviews and interrogations. We then created heatmaps to show which research topics have received substantial research attention and, importantly, where major gaps remain. Our findings show that although research in this field has grown considerably, the evidence is uneven. Some aspects of alcohol and eyewitness memory have been studied extensively, while many important questions—particularly those involving intoxicated suspects—remain largely unexplored. By mapping what we know and what we still need to learn, our study provides a roadmap for future research on alcohol and the justice system.

Why is it important?

Alcohol-intoxicated witnesses, victims, and suspects are frequently encountered by police and other legal professionals, yet there are limited evidence-based guidelines for how to handle intoxicated individuals in legal settings. This makes it important to understand not only what the research shows, but also where the evidence is strong enough to inform practice—and where it is still lacking. Our study is timely because research on alcohol and the legal system has grown substantially over the past 40 years, but no clear picture has existed of which questions have been well studied and which have been largely overlooked. By mapping the existing research, we show that the evidence is much stronger in some areas than in others. In particular, research on intoxicated suspects and interrogations remains very limited. Identifying these gaps can help researchers focus on the questions that most urgently need answers and help ensure that future policies and legal practices are based on robust scientific evidence. Ultimately, stronger evidence could contribute to fairer treatment of witnesses, victims, and suspects when alcohol is involved.