This review explored the key components of adolescents’ and youngsters’ perceptions of police legitimacy, thus contributing to a comprehensive, precise, and concise understanding of the relationships and dynamics between the police and the underaged. Specifically, we posed the following initial questions to guide the search. (1) How can we define police legitimacy and procedural justice for children and youth? (2) What are the determinants of police procedural justice and legitimacy for children and youth? (3) What are the consequences of police procedural (in)justice and (il)legitimacy for children and youth? (4) Among children and youth, who are the vulnerable groups receiving less legitimate and unjust treatment from the police?

We searched four databases for relevant studies: PubMed, Web of Science, Scopus, and ProQuest. These databases were selected based on the following criteria: (1) they covered social/behavioral science and health studies literatures, (2) they had “advanced search” options, allowing keyword searches with categories (see Figure 1), and (3) some of them were used in previous scoping reviews of legitimacy in prisons (Ryan and Bergin, 2022) and legitimacy in traffic rule compliance (Varet et al., 2021). The timeframe for the search was from January 1, 1990, to May 31, 2022. As the main theoretical framework for our research was the model developed by Tyler and colleagues in the 1990s (Tyler, 1990; Tyler and Lind, 1992), we set the start date for our literature search after the theoretical model was proposed.

Based on the research questions, three groups of keywords were used for searching (see Figure 1). In Figure 1 (from left to right), the three categories of keywords refer to the executor of the central concept (i.e., police), the central concept (i.e., procedural justice and legitimacy), and the target population (i.e., youth). The Boolean operators AND, OR, NOT, OR and NOT were also specified between the three groups of keywords in the search. The keywords within each category were interchangeable; thus, the Boolean operator “OR” was used. Meanwhile, the Boolean operator “AND” was employed to ensure that at least one keyword from each group was present in each result. The publications that included these combinations of keywords in their titles, abstracts, or keywords were the focus of this study.

Publications were included if they met each of the following criteria: (1) were scholarly refereed journal articles (book chapters, dissertation/thesis, etc. were excluded), (2) were empirical studies using quantitative, qualitative, or mixed method approaches (reviews, proceedings, letters to the editor, newsletters, etc. were excluded); and (3) were published in English. Overall, 1,863 references were found. After removing duplicate entries, 984 references were retained in the initial sample.

The third stage involved selecting the studies to be included in this review. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines (Liberati et al., 2009), the article selection was conducted manually in three rounds (see Figure 2). First, the second author independently classified the 984 articles into three categories: (1) articles beyond the scope of this review of police legitimacy (N = 799), for example, the focus was not on police officers exclusively nor procedural justice and legitimacy, (2) articles relevant to the scope (focus) of this review, but in which the age of the participants was outside the range of 7–18 years old (N = 107), and (3) articles considered relevant to the scope (focus) of this review in which the age of the participants was within the target range of 7–18 years old (N = 78). Only the 78 papers of the last category were included in the next step of the assessment.

In the second round, the first author conducted a quality assessment of the 78 articles identified in the first round, and the second author categorized the articles into two types (quantitative and qualitative studies) across five groups, including cross-sectional studies, qualitative studies, quasi-experimental studies, cohort studies, and randomized controlled trials. The Joanna Briggs Institute (JBI) is an evidence-based organization formed to develop methodologies and guidelines for conducting systematic or scoping reviews (Munn et al., 2014). It provides a checklist of 8–13 questions for evaluating the quality of studies with different research designs (see Joanna Briggs Institute, 2017, for full descriptions of the items in each checklist). For example, the items for assessing the cross-sectional studies include the following questions: (1) Were the criteria for inclusion in the sample clearly defined? (2) Were the study subjects and the settings described in detail? (3) Was the exposure measured validly and reliably? (4) Were objective, standard criteria used for measuring the condition? (5) Were confounding factors identified? (6) Were strategies to deal with confounding factors stated? (7) Were the outcomes measured validly and reliably? (8) Was appropriate statistical analysis used?

Based on the critical appraisal tools for assessing different research designs, the first two authors independently reviewed each article by answering either “yes, no, unclear, or not applicable (NA)” to each question in the checklist. Articles were removed if more than 20% of the questions in the checklist were answered “no, unclear, or NA.” Approximately 25 publications from the five groups of articles were dropped. The agreement rate in the first round was 84.62%. The two authors discussed the divergent decisions in the last round and reviewed these articles. After this step, 47 references remained (including 38 quantitative and 9 qualitative studies; see Tables 1, 2), and the agreement rate was 99%. The quantitative studies used cross-sectional, longitudinal, and experimental designs, and the qualitative studies used individual interviews, focus group interviews, and observation methods.

The relevant information was extracted from the selected publications, including author names, year of publication, location of the study, sample size and percentage of male participants, the mean age of the sample, types of the sample (e.g., general populations, school students, or offenders), research methods (study design for empirical studies or secondary data analysis), and main results. The studies were categorized into four groups (see Tables 1, 2).

Over the decades, police legitimacy has been defined or interpreted by legal, philosophy, and social sciences scholars. Beetham (1991, p. 16) argued that legitimacy can only exist when “it conforms to established rules, the rules can be justified by references to beliefs shared by both dominant and subordinate, and there is evidence of consent by the subordinate.” Tyler (2006, p. 376) defined legitimacy as “belief that authorities, institutions, and social arrangements are appropriate, proper, and just.” Bottoms and Tankebe’s (2012, p. 164) definition of legitimacy involves a “recognition of the moral rightness of claims to exercise power here and now, rather than in the future.” Murphy (2017, p. 45) put it: “Legitimacy reflects the degree to which people recognize the right of an authority to govern their behavior.” Clearly, as Cao (2022, p. 9) mentioned, the police legitimacy is “multidimensional,” and its concept is “quite liquid.”

The most common definition of procedural justice was the one used in Sunshine and Tyler (2003), Tyler (1990), and Tyler and Huo (2002), which emphasizes people’s perception or judgment of the fairness of procedures and treatment. Another definition of procedural justice was respectful, impartial, and unbiased treatment and voice (see Fagan and Tyler, 2005; Hamm et al., 2017; Jackson et al., 2013; Trinkner and Tyler, 2016). The third definition of procedural justice emphasized police officers’ effectiveness and distributive fairness (Tankebe, 2013) and their position as an appropriate authority entitled to obedience (Tyler, 2006).

Notably, although most scholars defined and measured the concepts of legitimacy and procedural justice separately (e.g., Fine et al., 2022), some scholars combined the two concepts into one by including procedural justice in the construct of legitimacy. For example, Nivette et al. (2020, pp. 71–72) concluded from their literature review that police legitimacy “is often used to capture broader perceptions of police performance, including procedural justice, lawfulness, trust, effectiveness, distributive justice, and obligation to obey the police.” Another example is the definition used by Liu and Liu (2018), which included procedural fairness and distributive fairness as two dimensions of legitimacy. The association between procedural justice and legitimacy was empirically tested in several studies. Among the 38 quantitative studies in this review, 11 specifically identified a significant positive association between procedural justice and police legitimacy. One exception was a longitudinal study (Pina-Sánchez and Brunton-Smith, 2020) that found no connection between perceptions of police procedural justice and legitimacy.

Demographic differences in gender, ethnicity (race), age, and household structure were controlled for and detected in most of the reviewed quantitative studies. However, the qualitative studies did not focus on demographic factors. Some studies discussed the impact of demographic and individual characteristics on police legitimacy.

Both quantitative and qualitative researchers contributed to conceptualizing and operationalizing police legitimacy. Among the 38 quantitative papers in this review, procedural justice, lawfulness, trust, effectiveness, distributive justice, obligation to obey the police, process fairness, and treatment fairness were used to measure police legitimacy. The terms mentioned in the previous sentence refers to the quality of treatment in police-youth encounters. Research focuses on how well the young people are handled by the police—involving a one-way, give-and-take relationship. Among the nine qualitative papers, more detailed and subjective conceptualizations were presented: friendliness, openness, accessibility, trust, peaceful and respectful interaction, and speaking to children and youth in schools and youth clubs. These are not only quality of treatment but also involve the interaction processing (or communication) and assessment of fulfilling personal expectations—involving a two-way, reciprocal relationship. We echo Bottoms and Tankebe’s (2012) argument that legitimacy is a dialogic process between power-holders (e.g., the police) and their audience (e.g., children and youth). Seemingly, a holistic perspective to understand the quality of treatment and interaction in encounters is imperative.

It is worth noting that 45 of the 47 studies were conducted in Western contexts; the exceptions were one from China and one from Africa. Whether the theoretical and conceptual understanding of police legitimacy can be applied to non-Western societies remains unclear. Cross-cultural comparisons and qualitative, in-depth, and contextual understandings of the definitions are warranted. Contextual understanding is essential, especially since we need to differentiate if people obey the law due to “true legitimacy”—their moral obligation to obey or “dull compulsion”—compliance is a result of “structurally-generated apathy,” “pragmatic acquiescence” “de facto authority” (Bottoms and Tankebe, 2012, pp. 148 and 165). Dull compulsion is more possible in those societies under authoritarian governance. We need to interpret the research data about people’s obligation to obey cautiously.

In the studies reviewed, the measurements of “global procedural justice” and “specific procedural justice” are not differentiated precisely. For instance, respondents were generally asked about the extent to which they perceived fairness and respect from the police. According to Gau (2014, p. 190), the former refers to “civilians’ general assessments of the overall levels of procedural justice that police provide to the public during typical face-to-face encounters” (p. 190), while the latter pertains to “evaluations made by individuals who have experienced face-to-face interactions with officers and are in a competent position to judge the extent to which officers acted with respect, fairness, and impartiality.” Essentially, the assessment of global procedural justice is not necessarily derived from firsthand experience; instead, media and vicarious experiences are major sources of judgment. Additionally, in many studies, while reporting factor loadings and Cronbach’s alphas is helpful, it is limited because the discriminant and convergent validity of these measurements have yet to be established (Gau, 2014). We endorse Gau’s perspective, advocating for confirmatory factor analysis to elucidate the underlying factor structure. Subsequently, employing structural equation models becomes imperative to discern the predictive interrelationships among these factors in quantitative inquiries.

The review supports a policing style characterized by fairness and justice and offers insights into promoting police legitimacy and mitigating the negative consequences of inadequate legitimacy.

First, from a crime control and prevention perspective, police legitimacy is valuable, as compliance with the law, obligation to obey, cooperation with and willingness to offer assistance to the police, and trust were associated with police legitimacy in nearly half of the studies. From the perspective of advancing children’s and youths’ well-being, police legitimacy is indispensable. Some studies demonstrated that propensity to retaliation, cynicism, and mental health issues are connected to diminished and inadequate perceptions of police legitimacy. Therefore, the need for police legitimacy and procedural justice is strongly justified by this review, not only because they improve society but also for the sake of citizens in general and minors in particular. Nevertheless, some scholars (e.g., Bottoms and Tankebe, 2012; Cao, 2022) reminded us of dull compulsion (i.e., people feel compelled to obey the order of authority or to obey the law for reasons other than legitimacy). We need to be aware of the differences in social and political contexts when interpreting the association between police legitimacy and compliance.

Second, the means used to achieve police legitimacy is a crucial question. Our findings indicate that establishing police legitimacy depends on several related and independent factors. These factors range from demographics (e.g., gender, age, and race/ethnicity) to personal qualities of youths (e.g., individuals’ legal and moral reasoning, self-justice retaliation, and self-control). Additionally, organizational and officer factors (e.g., police behavior, police contacts, and the relationships of youth with other authority figures) also matter. The social support system (e.g., parents, teachers, and legal practitioners), neighborhood circumstances (e.g., income level, and crime-rate), and societal influence (e.g., social media) also contribute significantly to the establishment of police legitimacy. Therefore, building and maintaining police legitimacy requires the intervention of multiple parties. For police officers, “the vital first step to building police legitimacy is to improve procedurally just policing practices through training, retraining, and oversight” (Fine et al., 2021, p. 15). Police leaders may need to actualize internal procedural justice (e.g., fair and just treatment of officers) so that supervisors and frontline officers can learn and apply it when dealing with the public. Indeed, internal and external procedural justice systems were shown to be connected in several studies, with officers who received supervisory procedural justice within an organization being more likely to render fair treatment to the public (e.g., Sun et al., 2018; van Craen and Skogan, 2017). Training in communicating with adolescents and ethnic minority groups, including skills such as active listening, empathic understanding, and rapport building with adequate cultural sensitivity, is essential for fair and quality policing. As children’s and youth’s relationships and interactions with their parents and teachers can impact their perceptions of police legitimacy, adults with a guardian role should be encouraged to instill proper legal and moral reasoning in the younger generation and to establish bonds with them. For example, Fine et al. (2021) concluded from a longitudinal study of 1,200 male adolescent offenders that parent training and family intervention are vital treatments for children and youth, demonstrating the possibility of intergenerational transmission of legal values and beliefs. For children and youth, assistance can be offered to enhance their moral reasoning and self-control abilities and to challenge tendencies to moral neutralization and self-justice retaliation. For example, Sheeran et al. (2022) mentioned a program entitled Students Talking it Over with the Police (STOP) specifically targeted youth. This program consisted of a standardized curriculum facilitated by two officers and taught to roughly 10 to 12 youths. The results indicated that participating in the STOP group significantly increased positive perceptions of the police. For this type of intervention, the collaborative effort between police officers and helping professionals, such as counselors and social workers, is critical. However, program providers need to bear in mind that the ultimate objective of those training programs is to promote “true legitimacy (i.e., compliance gained due to a perceived moral obligation to obey), not “dull compulsion” (compliance gained out of pragmatism or a result of de facto authority) (Bottoms and Tankebe, 2012, p. 165). Last, community leaders, especially those in high-crime neighborhoods, can mobilize local resources (e.g., venues, money, and volunteer workforces) to create opportunities for informal/positive contact between police officers and youngsters. In addition, communities can create drop-in centers staffed by social workers, mental health professionals, and other service providers (Slocum and Wiley, 2018). These collective efforts to restore social order can be helpful, as youth who experience less informal forms of social control in their neighborhoods view the police as less legitimate (Shook et al., 2021). However, such community initiatives rarely succeed without support from the government, especially in economically disadvantaged communities.

Third, the following problem deserves our efforts: determining a remedy for the harm to minors caused by a lack of procedural justice during contact (e.g., stops and searches) with the police. Such harm includes cynicism (i.e., a lack of empathy, defiance, impatience, and disregard for authority), the propensity to adopt self-justice retaliation (e.g., solving the problem through violence instead of calling the police), and adverse health consequences. For this reason, there is a high demand for the provision of services to arrested youth and children who have frequent police-initiated contacts on the street (e.g., delinquent youth). These vulnerable groups may need social workers to reach out and assist them in managing the anxiety, anger, and shame resulting from negative police encounters. Additionally, engaging underaged in a restorative justice program could be considered. In such a program, youths could voice their grievances about the perceived injustice, which might reduce their tendency to develop cynicism toward the police and government.

This review identified some knowledge and methodological gaps that can be filled by future research. First, most of the papers in this review used quantitative survey-based methods. Despite their empirical contribution, such quantitative methods cannot fill all the knowledge gaps, such as the effectiveness of police procedural justice practices in enhancing children’s and youth’s perceptions of police legitimacy. Evidence-based research using experimental designs can help to fill this gap. Some policing studies have adopted experimental designs, such as using a randomized controlled trial to evaluate the effectiveness of procedural justice training for officers (Antrobus et al., 2019), short procedurally just traffic encounters with the police (Mazerolle et al., 2013), or a factorial vignette design (Reisig et al., 2018), but such studies are rare. Second, procedural justice is process-based. Understanding the dynamics and interactions of the process is essential, and qualitative methods capture these elements more effectively than quantitative methods through the interviewees’ narratives. Accordingly, researchers must first be sensitive to the power and research ethics issues involved in such methods, such as confidentiality and gaining informed consent in the data collection process from vulnerable groups, including children and youth.

Third, as perceptions and judgments of police behavior are situational, methods that use scenarios and vignette cases may help to unpack the complexity of these concepts. For example, Trinkner et al. (2019) conducted a vignette-based experiment that manipulated two aspects of officer behavior linked to the perceptions of police fairness: voice and impartiality. The application of vignettes in this study helped confirm that both the voice and impartiality manipulations impacted judgments of situational procedural justice. The use of vignettes in this field of study should be encouraged. Indeed, diversification methodologies to understand perspectives in the research of police legitimacy may help to unpack the theoretical model with reference to the context of policing (Graham, 2022). Fourth, as proposed by Sun and Wu (2022), further studies should be conducted to examine other consequences of legitimacy. For instance, none of the studies in this review considered the links between legitimacy or illegitimacy and the mental health and academic issues confronting children and youth. One study found that being stopped by the police was linked to diminished educational expectations among youth (Jackson et al., 2022) and that procedural justice can buffer the hostile experience of police encounters on the post-traumatic stress symptoms of youth (Gearhart et al., 2023). These two recently published papers were excluded from this review because they were not within the publication period initially set in the search criteria. Finally, consistent with the view of Sun and Wu (2022) that disadvantageous populations other than ethnic minority groups should be included in future research, we argue that future studies could further examine the perceptions of police legitimacy of minority groups (e.g., LGBTQ+, individuals with mental and learning disabilities, and new immigrants) and police self-legitimacy (i.e., officers’ belief about their own legitimacy).