In 2001, the National Research Council (NRC) report, Juvenile Crime, Juvenile Justice, focused on the causes and responses to juvenile crime (National Research Council and Institute of Medicine, 2001). The study came on the heels of rising violent juvenile crime and a wave of state statutes imposing tougher sanctions on juvenile offenders, including the transfer of juveniles to criminal courts at younger ages. The NRC panel observed that the spike in serious juvenile crime during the late 1980s and early 1990s was mainly attributable to gun homicides associated with the crack epidemic and that serious juvenile crime was already declining when most of the punitive statutes were being enacted.
Much has occurred since the publication of Juvenile Crime, Juvenile Justice. First, there has been an explosion of knowledge regarding adolescent development, especially in increased understanding of the neuro-biological underpinnings of the behavioral differences associated with this distinct period of human development. In addition, much has been learned about the pathways to delinquency and patterns of offending, the efficacy and cost-effectiveness of prevention and treatment programs, and the long-term effects of confining youth in secure or harsh conditions and transferring them to the adult system. Significantly, the rate of offending among both juveniles and adults has continued to decline.
The wisdom of the “get-tough” policies of the 1990s has been widely questioned based on growing doubts about their effectiveness in reducing offending and increasing concern about their high costs in the face of declining state budgets. As a result, many state and local jurisdictions have undertaken significant steps to reverse these measures and, more generally,
to overhaul their juvenile justice systems. This impressive reform movement has been propelled by a coalition of child advocacy organizations, private foundations, and political leaders. Juvenile justice reform is once again “in the air,” just as it was during the 1990s—this time, however, the emerging consensus is that the juvenile justice system should be strengthened rather than contracted and that it should be grounded in the advancing science of adolescent development rather than treating offending youth as emerging adult criminals.
It was in this context that the Office of Juvenile Justice and Delinquency Prevention (OJJDP) asked the NRC to take stock of the new wave of reforms undertaken since the 2001 study. OJJDP, established in 1974, is the agency through which the federal government can help state and local governments prevent and control juvenile delinquency and improve juvenile justice systems. A key aim was to protect juveniles from harm, both physical and psychological, that could occur as a result of inappropriate placements and from exposure to adult inmates. Through funding incentives, OJJDP encourages states to incorporate core protections1 into their juvenile justice practices. For more information on OJJDP’s role and its assistance to state and local governments, see Chapter 10.
The Committee on Assessing Juvenile Justice Reform was charged with conducting a study to assess the implications of recent advances in behavioral and neuroscience research for the field of juvenile justice, to assess the new generation of reform activities occurring in the United States, and to assess the performance of OJJDP in carrying out its statutory mission as well as its potential role in supporting scientifically based reform to improve the fair and equal treatment of delinquent youth.
The specific primary tasks of this study were to:
- review the science of childhood and adolescent development and identify relevant findings for juvenile justice;
- describe the history of juvenile justice reform, its stages, major legislative and judicial changes, and the driving forces behind the current rethinking of policies and programs;
- provide a current context for understanding the implications of developmental behavioral and neuroscience research for juvenile justice policies and programs;
1 OJJDP’s authorizing legislation ties four core requirements to state formula funding: deinstitutionalization of status offenders, removal from adult jail and lockup, sight and sound separation, and reduction of disproportionate minority contact.
- identify current juvenile justice reform efforts occurring at the state and local level and review available evidence regarding the effectiveness of these initiatives;
- review the activities of OJJDP in carrying out the legislative mandates in the Juvenile Justice and Delinquency Prevention Act (JJDPA) of 1974 as subsequently amended;
- assess OJJDP’s capacity to promote and support scientifically based reforms aimed at reducing crime and providing for the fair and safe treatment of juveniles; and
- make recommendations to advance theory and research and to improve state and federal juvenile justice policies and practices.
The current report builds on and complements the earlier NRC report but differs substantially from it. Rather than focusing on the causes and characteristics of juvenile crime, we focus solely on the policies and practices of the juvenile justice system and on the aspects of adolescent development that bear on its design and operation. We aim, in short, to contribute to the transformation of juvenile justice that is already under way by consolidating its scientific foundation and pointing the way toward effective implementation. This report is being written at a time when policy makers seem particularly receptive to evidence-based policies, programs, and practices that are known to be effective in preventing juvenile crime. After a period of serious conflict about the mission of the juvenile justice system (sometimes questioning its very existence), a new consensus is emerging regarding the need for a separate justice system for adolescents. However, this consensus is neither fully developed nor deeply rooted. This report has two goals: (1) to show that the emerging consensus rests on strong scientific and normative foundations and (2) to set forth a framework for a developmentally informed juvenile justice system, for incorporating new evidence into policy and practice on a continuing basis, and for solidifying and sustaining these changes over the long term.
The committee held six meetings during the course of the study. The first three were information-gathering meetings at which we heard presentations from a variety of stakeholders, including representatives from OJJDP, foundations, academia, state and local juvenile justice agencies, and research and legal institutions, as well as a young adult who had served time in the adult criminal justice system as an adolescent. The last three meetings were closed to the public in order for the committee to deliberate on the report and finalize our conclusions and recommendations.
The committee reviewed multiple sources of information as background for the study: research literature on adolescent development, juvenile crime, and the treatment of juvenile offenders, as well as materials on the legislative history of the JJDPA; the grant programs of OJJDP and other federal agencies, including available financial data; current reform efforts at national, state, and local levels; and practitioner experiences with implementing the core requirements of JJDPA and responding to shifts in youth crime prevention and control policies. We also commissioned a paper on the Missouri juvenile justice system.
A word is in order regarding some of the terminology used in this report. There is no common agreement in the juvenile justice field about a number of terms used in this report. The committee struggled with this and in an effort to provide uniformity it has tried to use the definitions that follow. But it is important to point out that we have had some difficulty always applying these definitions when reviewing the literature, because they are ours and not necessarily those of the field.
As with the earlier 2001 NRC report on juvenile crime, the committee uses the term “juvenile” to refer to anyone under the age of 18, unless otherwise specified.2 Other terms used synonymously with juvenile include “young person” and “youth.” For the analyses of crime trends in this chapter, “juvenile” refers to those between ages 10 and 17, because those under age 10 are seldom arrested.
“Adolescence” is the pivotal concept used in this report. Scientifically speaking, adolescence has no finite chronological onset or end-point, and there is no legal definition of adolescence per se because the law regards different ages as being legally relevant in different contexts. The science of adolescence refers to a phase in development between childhood and adulthood beginning at puberty, typically about 12 or 13 and ending in the late teens or early 20s. Generally speaking, however, the committee focuses on youth under age 18, typically the age of majority and the ceiling of delinquency adjudication in most states. In the few instances in which we mean to encompass youth older than age 18, a specific statement is made.
The terms “delinquency” refers to acts by a juvenile that would be considered a crime if committed by an adult, as well as to actions that are illegal only because of the age of the offender. “Juvenile crime” or “criminal delinquency” refers to more serious acts that would be crimes if commit-
2 Technically, “juvenile” is a legal definition referring to the jurisdictional age of each state’s juvenile court or family court system and includes those youth who fall under the purview of the state’s delinquency code and not the criminal code.
ted by adults. “Status delinquency” offenses include truancy, running away from home, incorrigibility (i.e., habitually disobeying reasonable and lawful commands of a parent, guardian, or custodian; also referred to in various statutes as unruly, uncontrollable, or ungovernable behavior), and liquor law violations.3 In some states, status delinquents are referred to the child welfare or social service systems, and in others status delinquents are dealt with in the juvenile justice system.
“Adjudicated delinquent” or “delinquent” is used synonymously to describe the individual who has been found by the juvenile court to have committed a juvenile crime. The committee uses the term “justice-involved youth” to refer to youth who have contact with any form of legal authority, including police diversion, and “juvenile offenders” or “youthful offenders” for those who are referred to court or juvenile intake after police intake. For reasons mentioned below, this report does not distinguish between serious juvenile offenders and the general population of youthful offenders, except where noted.
Finally, one of the most controversial issues in the administration of juvenile justice relates to the use of confinement, either after the juvenile has been taken into custody and charged with delinquency or as a formal disposition after an adjudication of delinquency. This report uses the term “confinement,” depending on the context, to refer to detention before adjudication or to placement in a custodial setting as a disposition after a finding of delinquency. In the dispositional context, it encompasses what are typically called institutional placements or out-of-home residential placements. It is not meant to encompass day treatment or nonresidential, community-based therapeutic programs.
THE COMPLEX MISSION OF JUVENILE JUSTICE
America’s system of juvenile justice was founded on the premise that, because of their immaturity, young people accused of crimes should be treated differently from adults. Ideally, the juvenile justice system is more responsive than the criminal justice system would be to the developmental characteristics of children and youth. The sanctions prescribed and services provided by the juvenile system should be designed not only to hold youth accountable but also to address the causes of their misbehavior, reduce reoffend ing, and facilitate positive and healthy adolescent development. The long-term goal of any intervention is to restore the youth to full and responsible membership in his or her family as well as the larger community.
3 Legally, delinquent acts are akin to criminal acts, and status offenses are noncriminal acts akin to civil violations based on age. It is important to note also that states vary considerably in the language they use to denote status offenses.
A developmental approach to juvenile justice recognizes that illegal acts committed by adolescents occur in the context of a distinct period of human development, a time of life when individuals are more likely to exercise poor judgment, take risks, and pursue thrills and excitement. This naturally results in a higher incidence of illegal behavior. Most young people involved with the juvenile justice system will desist from criminal behavior simply as a result of maturation, although the timing and trajectories of desistance vary considerably (Laub and Sampson, 2001).
The U.S. system of juvenile justice authorizes legal intervention in all forms of adolescent offending, from nearly trivial to life-threatening offenses. As traditionally understood, the purpose of intervention in each case is to prevent the escalation of illegal behavior while not damaging the life chances of young people with punitive and permanently stigmatizing criminal sanctions. However, the boundaries between juvenile court dispositions and criminal sanctions have become blurred during the past two decades, allowing delinquency adjudications to establish the legal predicate for sex offender registration and to count as prior convictions for criminal sentencing purposes.
The legal traditions of juvenile justice rest on an awkward blend of civil and criminal law. That is why the juvenile justice system is sometimes described using terms from the realm of social welfare, and at other times drawing on the vocabulary of criminal law. The judicial discretion and more flexible procedures characteristic of the juvenile legal system (for example, the absence of a jury trial) are intended to achieve a number of important goals simultaneously.
The goal of delivering services to reduce the risk of reoffending is deeply grounded in the origins of juvenile justice. For more than a century since the founding of the first juvenile court in 1899, the juvenile justice system has justified its existence by being more treatment oriented and more rehabilitative than its criminal counterpart—indeed rehabilitation has been abandoned as a goal of criminal justice in most modern criminal codes. By contrast, treatment is the juvenile justice system’s very reason for being. An industry of treatment providers has emerged to support this treatment mission by delivering therapeutic interventions to address family conflict, cognitive deficits, drug abuse, and mental health issues, including a growing number of programs that are now supported by high-quality evaluation evidence.
The successful juvenile court must deliver needed services while ensuring accountability and protecting the community. The young person before the court is at once a potential beneficiary of the intervention and a target of accusation and judgment. If these tensions were not already complicated enough, it is essential to remember that the young person is also a holder of rights. Whatever the society’s motivation for intervening (rehabilitation
or accountability), the young person is legally entitled to be treated fairly, and the Constitution requires juvenile justice to adhere to the basic requirements of due process, including representation by counsel in a trial at which the prosecution is required to prove the elements of the delinquent offense beyond a reasonable doubt. But fairness is also important from a social science perspective and, while the research is limited, there is some indication that perceptions of fairness on the part of youth and families also are important in achieving the juvenile court’s objectives.
In the committee’s view, looking at juvenile justice through the prism of adolescent development helps to reconcile these tensions. Holding youth accountable for wrongdoing and treating them fairly can facilitate successful socialization and thereby reduce the risk of reoffending. That is not to say that the task is an easy one. Many obstacles must be overcome to initiate and sustain juvenile justice reform. However, the committee is optimistic about the prospects for success.
Two important topics must be addressed before undertaking the basic narrative of the committee’s report. First, the committee’s focus on juvenile justice should not be understood as deemphasizing the importance of investing in programs and services that can prevent delinquency in the first place. Second, we also want to take note of the heterogeneity of adolescent offending. Policy makers might imagine that the best way to reconcile the tensions in the mission of juvenile justice is to sort offenders into categories, using seriousness of offending as proxies for maturity, culpability, social danger, or amenability to rehabilitation. However, it is important to recognize from the outset that this strategy is generally not scientifically supportable. There may be other reasons to draw legal distinctions based on offense categories, but they are generally unsupported by criminological data.
This report focuses on the role of the juvenile justice system in promoting accountability and preventing reoffending once a youth is already in contact with the system. However, we are certainly mindful that serious adolescent behavior problems do not spring up suddenly in adolescence. From a developmental perspective, youth at highest risk accumulated these risks from childhood and often from infancy and before birth. Moreover, we are also mindful that poverty, social disorganization, and other serious structural issues in many communities propel vulnerable adolescents toward delinquency, and that local officials in these communities all too often tend to see the juvenile justice system as the standard intervention
rather than as a last resort. For this reason, it is important to emphasize at the outset of this report that findings in developmental science provide a strong rationale for investing in early prevention programs, that empirical evidence regarding the efficacy of specific prevention programs is growing, and that OJJDP is charged with providing federal leadership in delinquency prevention.
Developmental science findings indicate that children who are at risk for persistent delinquency can be identified early in life with relative accuracy (Moffitt et al., 2011), providing targets for prevention programs. Findings also identify theoretically coherent risk and protective factors, beginning at or before birth, that provide substantive foci for interventions. The findings provide the rationale for early prevention programs that have been evaluated through randomized controlled trials and found to reduce risk for delinquency. The most effective programs are ones that target multiple domains of parenting, children’s social-cognitive skills, and school success. Programs directed toward demographically high-risk families in the first several years of life focus on supporting parenting and/or delivery of high-quality preschool day care, including the Abecedarian Project (Campbell and Ramey, 1995), the Child-Parent Center Education Program (Reynolds et al., 2011), the Nurse Family Partnership (Olds et al., 1998), and the Perry Preschool Program (Heckman et al., 2010). A meta-analysis by Piquero et al. (2009) revealed that these programs, on average, are not only effective but also may be wise economic investments because of the savings that accrue over a youth’s life course.
Programs in middle childhood target parenting and social-cognitive skills among early-starting children with conduct problems, including Anger Coping (Lochman and Wells, 2004), the Fast Track Program (Conduct Problems Prevention Research Group, 2010), GREAT Schools and Families (Multisite Violence Prevention Project, 2009), and the Montreal Longitudinal Experiment (Boisjoli et al., 2007). An effective approach with African American boys is to help them alter hostile attributional biases (Hudley and Graham, 1993). Middle school curricula in social-cognitive development, such as Life Skills Training (Botvin et al., 2006), prevent adolescent substance use and antisocial behaviors. In order for these programs to have a population-level effect, major systems in children’s lives—school, family, health, housing, community—must support and coordinate their services. For a recent review of the prevention literature, the reader is also referred to Preventing Mental, Emotional, and Behavioral Disorders Among Young People: Progress and Possibilities (National Research Council and Institute of Medicine, 2009).
Heterogeneity of Juvenile Offending
Although this report focuses on the design and operation of the juvenile justice system, it is important to have a sense of some general characteristics of the offending behavior to which the system is expected to respond. Research on juvenile offending4 reflects substantial heterogeneity in the population of youth who can be considered delinquent. At one extreme, some youth commit only a few trivial offenses; at the other extreme, some youth commit many offenses, some of which are quite serious and violent.
The epidemiological literature shows that, regardless of how serious delinquents are defined,5 they constitute a very small proportion of the overall delinquent population. They do commit many offenses, but most of their offenses are relatively minor and there are extraordinarily few chronic violent offenders. The vast majority of youth who are arrested or referred to juvenile court are not serious delinquents, and half of them appear in the system only once.
Concern over serious delinquents emerged from the pioneering longitudinal studies of Wolfgang and colleagues (Wolfgang et al., 1972, 1987; Wolfgang, 1983) in their study of the 1945 birth cohort of males in Philadelphia. Using official arrest data to measure delinquency, they identified a group they called chronic offenders, youth who had been arrested five or more times. Although constituting only 6 percent of the total cohort and 18 percent of the delinquents (those who had been arrested at least once), chronic offenders were responsible for 52 percent of all the offenses committed. They also committed serious and violent offenses at a higher than average rate. Their disproportionate contribution to the overall delinquency rate garnered great attention, in terms of both research and policy. Although the identification of this group of chronic offenders was important to juvenile justice policy, it is also worth recalling another finding from the Philadelphia study: almost half of the delinquents (46 percent) were one-time offenders and almost two-thirds (65 percent) of the offenders were arrested no more than twice. Similar results were also found in the 1958 Philadelphia birth cohort (Kempf-Leonard et al., 2001).
4 It is also important to bear in mind that there are important methodological differences across criminological studies with respect to who is studied and how. All of this variation can influence the observed results and needs to be kept in mind in interpreting research findings. For further discussion of this, see Box 1-1 at the end of this chapter.
5 There is no clear, generally agreed-upon definition of what it means to be a serious delin quent. Some studies of serious delinquents focus just on the seriousness of the offenses that are committed, some on the frequency of their offending, and others on involvement in violent behavior (Loeber and Farrington, 1998). In addition, some studies focus on the co-occurrence of these dimensions as they tend to be interrelated (Loeber, Farrington, and Waschbusch, 1998; see also Kempf-Leonard et al., 2001). For example, youth who are high-frequency offenders are also more likely to commit violent and serious offenses at a higher rate than others.
Since this early work, a number of studies have examined serious chronic offenders (Loeber and Farrington, 1998). Perhaps the most thorough investigation was conducted by Snyder (1998) who found that a majority of the youth referred to juvenile court in Maricopa County, Arizona, did not meet criteria to be placed into the categories of chronic offender (referred four or more times), violent offender, or serious but nonviolent offender. Indeed, 63.9 percent of all referred youth were not considered as any of these, and 29.5 percent were considered serious but nonviolent offenders. Moreover, the majority of referred youth were one-time offenders. This finding is echoed by Kempf-Leonard et al. (2001) and van der Geest et al. (2009), both of whom found that the majority of their sample did not commit violent offenses.
Snyder (1998) also found that the chronic offenders were responsible for a disproportionate proportion (44.6 percent) of all offenses referred to the court. Perhaps the public’s greatest fear is focused on chronically violent delinquents, that is, youth who frequently commit violent offenses. Yet this group is exceedingly rare. Of the 151,209 referred youth, Snyder found that only 168 were referred for four or more violent offenses. This represents only 0.1 percent of all referred youth and 1.4 percent of those youth ever referred for a violent offense. This finding continues to be reflected in recent estimates where Esbensen et al. (2010) presented concordant national-level data: “a rough approximation can be made that only .74 percent of all juveniles [aged 10 to 17 in the United States] were arrested for simple assault in 1995” (2010, p. 42). Similarly only .29 percent were arrested for aggravated assault and .20 percent for robbery. Examining the most serious offense type, homicide and nonnegligent manslaughter, the actual prevalence and proportion of offenses committed by those under age 15 is negligible (.08 percent).
Piquero (2008b) conducted an extensive review of the trajectory literature (e.g., Nagin and Land, 1993; Sampson and Laub, 1993a; Brame, Mulvey, and Piquero, 2001; Ezell and Cohen, 2005) based on over 80 longitudinal studies. He reports considerable consistency across these studies which were conducted with very different samples and in several countries. Although the number of trajectory groups varies somewhat across studies, these studies overwhelmingly find evidence that there is a large group of youth who are either nonoffenders or who offend at a very low rate at one extreme and a numerically small group of chronic offenders at the other extreme. This pattern is similar to that found in the earlier studies by Wolfgang, Figlio, and Sellin (1972) and Snyder (1998).
Recent summaries of analyses of longitudinal data sets indicate that approximately one-third of adolescents with an arrest record go on to an adult arrest; two-thirds do not. The consistency of offending varies by era, gender, race/ethnicity, and age of onset of offending, with ado-
lescents who begin offending at a younger age more likely to be adult offenders (Kazemian, Farrington, and LeBlanc, 2009; Piquero, Hawkins, and Kazemian, 2012). Estimates of the continuity of offending also vary depending on whether self-report or arrest is used as the indicator of criminal activity (Loeber et al., 2008). Depending on where the sample of juvenile offenders is drawn from in the juvenile justice system, in almost all studies, however, only a minority of juvenile offenders do become adult criminals. Even in a sample of serious (felony level) juvenile offenders, the majority of adolescents report very low levels of offending three years after court involvement (Mulvey et al., 2010).
In addition, juvenile and adult offenders reduce criminal behavior over time enough to be indistinguishable in their risk of offending from individuals who have never committed a crime (Kurlychek, Brahm, and Bushway, 2007; Blumstein and Nakamura, 2009). The time until an individual reduces his risk of offending to that of others his age varies by offense and age of the first arrest. It is worth noting, though, that a juvenile arrested at age 16 for robbery has the same likelihood of arrest as his peers when they are 24.5 years old (Blumstein and Nakamura, 2009).
Numerous theories exist about why youth persist or desist from crime, and it is generally recognized that the factors that promote desistance may be distinct from the factors that support the maintenance of a criminal lifestyle. Theories about desistance revolve around the relative influence of stable, individual differences (in traits like self-control or intelligence), the effects of developmental factors associated with late adolescence (like increased consideration of others, sense of agency, or brain maturation), and the impact of dynamic life changes (like romantic relationships or stable employment). While there is considerable empirical support for a number of these ideas, the evidence overall appears to support an interactionist view of an individual’s psychological and social assets, their current developmental challenges, and the occurrence of normative and unexpected life events (see Thornberry et al., 2012). The extant capacity of adolescents and young adults to address the emerging challenges and roles of early adulthood, interacting with the skills and social resources that they might acquire during this period, make the difference in reducing antisocial activity. There is considerable work ahead, however, to fill in the picture of how these multiple factors mesh together to promote desistance (Laub and Boonstoppel, 2012).
The juvenile justice system needs to respond forcefully to serious, chronic, and violent offenders, but it should always be recognized that the proportion of youth who fall in this category, even among youth referred to the juvenile justice system, is quite small. We recognize that serious chronic delinquents may need to be dealt with differently from other offenders, including more reliance on secure confinement in order to protect pub-
lic safety. But as the report discusses, the behavior of these youth is still driven by the same risk factors and developmental processes that influence the behavior of other delinquents. For that reason, the committee has not included a separate chapter singling out this small subgroup of serious delinquents. Instead, we consider the entire population of juvenile offenders, noting when appropriate specific differences that arise for serious, violent, or chronic offenders.
Chapter 2 describes the history of the juvenile court and its shifting goals, with a particular emphasis on the harsh policies of the 1990s and the emergence of a contemporary model of juvenile justice in the 21st century. It explains the role of scientific research in this most recent reform period and its influence on attitudes, policies, and programs. Chapter 3 provides an overview of the current practice of juvenile justice in the United States and the characteristics of juvenile justice administration that make reform difficult and uneven. Chapter 4 reviews the body of behavioral, psychological, and neuroscience research demonstrating that adolescence is a distinct period of human development differing in fundamental ways from both childhood and adulthood. Chapter 5 draws out the implications of a developmental perspective for design and operation of a fair and effective system of juvenile justice. Chapter 6 focuses specifically on the body of research bearing on the most effective policies and programs for preventing reoffending by youth who have come to the attention of the juvenile court. Chapter 7 explores the implications of the developmental perspective for designing a fair and effective process for holding youth accountable for their wrongdoing. Chapter 8 provides an overview of the problem of racial/ethnic disparity in the juvenile justice system, reviews the contending explanations for minority overrepresentation, and identifies strategies for moving beyond the current impasse. Chapter 9 describes the major juvenile justice reform initiatives undertaken over the past two decades and identifies the key lessons that can be drawn from these experiences to guide jurisdictions embarking on the path of developmentally informed reform. Chapter 10 is an overview of OJJDP’s legislatively mandated role in helping state and localities strengthen their juvenile justice systems and make them more fair and equitable. It describes OJJDP’s current weakened status and the steps that will be needed to restore its leadership capacity to promote the developmentally appropriate treatment of juveniles by the justice system. Chapter 11 concludes the report with the committee’s recommendations for achieving a fairer and effective system of juvenile justice based on a developmental approach.
The report contains four appendixes. Appendix A supplements the report’s discussion of the benefits and costs of juvenile offender programs by describing the methodological challenges in undertaking such analyses and the strong evidence regarding the financial benefits of evidence-based programs. Appendix B provides detailed information on the history and characteristics of the widely replicated Missouri model of juvenile justice and an assessment of its effectiveness. Appendix C examines OJJDP’s role in mentoring, a program heavily supported by Congress, and reviews research bearing on its effectiveness as a prevention program. Appendix D presents biographical sketches of committee members and staff.
Methodological Differences of Criminological Studies
Many studies are based on representative, community samples of adolescents, some of whom are delinquent and some of whom are not. The purpose of these studies is to compare delinquents with nondelinquents, for example, to identify risk and protective factors. Studies of this type include Wolfgang et al. (1972), Elliott et al. (1989), Farrington (1989), and the projects of OJJDP’s Research Program on the Causes and Correlates of Delinquency (Huizinga, Loeber, and Thornberry, 1995). Many other studies focus solely on youth who have already had contact with the juvenile justice system. Although these studies examine different types of young offenders, recidivism and desistance, and related topics, the sample numbers are based on youth officially identified as delinquent. Studies of this nature include Snyder (1998), Ezell and Cohen (2005), and Mulvey et al. (2010).
In addition to variability by type of sample, there is also a fundamental difference in the manner in which delinquent behavior is measured in criminological studies. Many studies use official or archival data to assess whether a participant is a delinquent and, if so, the number and types of offenses committed. The most typical measures are arrest or adjudication records. Many other studies use self-reported data in which the study participants are surveyed and asked to report on their own involvement in delinquent behavior. In addition, some studies use both types of information—official measures and self-report measures—for the same participants. There is some relationship between the type of sample and the type of measure likely to be found in a given study. That is, studies of general community samples are likely to use self-reported measures, and studies of youth in the juvenile justice system are likely to use official measures. But that correlation is far from perfect. For example, the study by Wolfgang and colleagues (1972), based on a community cohort, uses only official data, whereas the study by Mulvey and colleagues (2010), based on an adjudicated sample, relies extensively on self-report measures.
Each strategy for sampling and for measurement has strengths and weaknesses. With respect to sampling, community samples are more representative of the total adolescent population and allow for important comparisons between youth who have committed delinquent acts and those who have not.* They often contain few very serious offenders, however, and are hampered in their investigation of juvenile justice system processes. In contrast, studies based on only adjudicated youth are likely to contain a higher representation of serious offenders and more direct information about how the juvenile justice system operates and how it influences delinquent careers. But, by definition, these studies do not
include a comparison group of nondelinquents, and findings based on these samples cannot be generalized to the total adolescent population. Similarly, with respect to measurement, official measures may provide greater certainty that those identified as delinquent are, in fact, delinquents, but the heavy screening that occurs between the commission of an offense and the likelihood of arrest and adjudication means that the vast majority of youth who actually commit delinquent behaviors are not categorized as delinquent. In other words, they grossly undercount the number of delinquents and the number of delinquencies. In contrast, the self-report method provides a fuller accounting and is much more apt to identify all the youth who commit delinquent acts as delinquents, but they often underestimate the rate of serious and violent offending (Thornberry and Krohn, 2000).
These methodological issues can influence the results observed in studies and provide somewhat different images of the delinquent population and the developmental processes that lead to offending. Even something as basic as estimates of the prevalence of delinquency—the percentage of the population that engages in this behavior—differ. Based on self-reported delinquency studies, virtually everyone commits at least some delinquent acts during adolescence, and most report committing several (Short and Nye, 1958; Elliott, Huizinga, and Ageton, 1985; Huizinga et al., 1993). From this perspective, delinquent behavior could be considered “age-normative”—a part of the normal developmental process of moving through the teenage years. In contrast, in studies based on official measures, such as arrest or adjudication, delinquent behavior, especially repeated delinquent behavior, is committed only by a distinct minority of the adolescent population.
There are also differences in the basic correlates of delinquency, for example, by race/ethnicity, social class, and gender. In general, subgroup differences are greater when official data are used and considerably reduced when self-reported data are used.
Neither of these approaches to research—community versus juvenile justice samples or official versus self-report measures—is better than the other. As noted above, each has advantages and disadvantages. They are also designed to address somewhat different questions. For example, representative, community samples are more appropriate for identifying risk factors and causes of offending. Juvenile justice samples are more appropriate for studying the impact of new policies and practices in the juvenile justice system on various outcomes. Throughout this report, we rely on both types of studies and both types of measures as appropriate to the question at hand.
* It is important to point out that youth who are classified as nondelinquent may, in fact, have committed a delinquent act but have managed to evade detection.