There is hardly a more contentious issue in American society than the ownership of firearms and various proposals for their control. To make reasonable decisions about these matters, public authorities must take account of conflicting constitutional claims and divided public opinion as well as the facts about the relationship between firearms and violence. In performing these tasks, policy makers must try to strike a reasonable balance between the costs and the benefits of private firearm ownership.
The costs seem obvious. In 2000, over 48,000 victims suffered nonfatal gunshot wounds (Centers for Disease Control and Prevention, 2001) and over 10,000 were murdered with a firearm (Federal Bureau of Investigation, 2001). Many more people, though not shot, are confronted by assailants armed with a gun. Young people are especially affected by this, so much so that firearm fatalities consistently rank among the leading causes of death per capita for youth. In 2000, people ages 20 to 24 accounted for almost one-fourth of all victims of homicides with a firearm (Federal Bureau of Investigation, 2001). Moreover, there are more suicides than homicides that are committed with firearms. And firearm-related accidents result in many serious injuries.
These grim facts must be interpreted with caution. Firearms are involved in homicides and suicides, but determining how many would have occurred had no firearm been available is at best a difficult task. Between 1980 and 1984 there were more than three times as many nongun homicides per capita in America than in England (Zimring and Hawkins, 1998). There were over 41,000 nongun homicides and over 63,000 gun homicides in the United States during this period. New York City has had a homicide rate that is 8 to
15 times higher than London’s for at least the last 200 years, long before either city could have had its rates affected by English gun control laws, the advent of dangerous drugs, or the supposedly harmful effects of the mass media (Monkkonen, 2001). Thus, the United States arguably has a high level of violence and homicide independent of firearm availability. Nonetheless, today homicides by a firearm occur in the United States at a rate that is more than 63 times that of England, so firearms, though not the sole source of violence, play a large role in it (Zimring and Hawkins, 1998).
The problem is the same with suicide. People often kill themselves with firearms. There is some evidence that states with the highest rates of private firearm ownership tend to be those with the highest proportion of suicides committed with firearms (Azrael et al., 2004), and there are studies suggesting that homes with firearms in them have more suicides than homes without firearms (Hardy, 2002). However, it is difficult to determine how many people would kill themselves by other means if no firearms were available.
Explaining a violent death is a difficult business. Personal temperament, mental health, the availability of weapons, human motivation, law enforcement policies, and accidental circumstances all play a role in leading one person but not another to inflict serious violence. Furthermore, the impact that a gun has on a situation depends critically on the nature of the interaction taking place. A gun in the hand of a robber may have different consequences than a gun in the hands of a potential robbery victim, a drug dealer, or someone who is suicidal. The relationship between the individuals may also be important in determining the impact of a gun. In a domestic dispute, for instance, both parties might be well informed as to whether the other person has a firearm. In a burglary or street robbery, the offender is less likely to know whether the victim is armed.
In addition, the presence or threat of a gun may influence an interaction along multiple dimensions. A firearm may increase or decrease the likelihood that a potentially violent situation will arise. For instance, an offender with a firearm may be more likely to attempt a robbery, but knowing the victim has a firearm may lead the offender to forgo the crime. The presence of a firearm may also affect the likelihood that an interaction ends in violence or death. For example, it might be that the presence of a gun in a robbery is associated with higher death rates, but lower injury rates.
The intent of the persons, the nature of their interaction and relationships, the availability of firearms to them, and the level of law enforcement are critical in explaining when and why firearm violence occurs. Without attention to this complexity it becomes very difficult to understand the role that firearms play in violence. Even if firearms are shown to be a cause of lethal violence, the development of successful prevention programs remains a complex undertaking, as such interventions would undoubtedly have to address the many factors other than the firearm that are involved in any violent situation.
Many people derive benefits from firearm ownership. Some people
hunt or shoot at target ranges without ever inflicting harm on any human. It is estimated that there are 13 million hunters in the United States (U.S. Department of the Interior, Fish and Wildlife Service, 2002) and more than 11,000 shooting tournaments sanctioned by the National Rifle Association each year (National Rifle Association, 2002). Others have firearms because they believe the weapons will help them defend themselves. Many people carry their weapons on their person or in their cars. We do not know accurately how often armed self-defense occurs or even how to precisely define self-defense. The available data are believed to be unreliable, but even the smallest of the estimates indicates that there may be hundreds of defensive uses every day (Cook, 1991; Kleck and Gertz, 1995).
Given the importance of this issue and the continued controversy surrounding the debate on firearms, the need was clear for an unbiased assessment of the existing portfolio of data and research. Accordingly, the National Academies were asked by a consortium of both federal agencies—the National Institute of Justice and the Centers for Disease Control and Prevention—and private foundations—the David and Lucile Packard Foundation, the Annie E. Casey Foundation, and the Joyce Foundation—to assess the data and research on firearms.
The Committee to Improve Research and Data on Firearms was charged with providing an assessment of the strengths and limitations of the existing research and data on gun violence and identifying important gaps in knowledge; describing new methods to put research findings and data together to support the design and implementation of improved prevention, intervention, and control strategies for reducing gun-related crime, suicide, and accidental fatalities; and utilizing existing data and research on firearms and firearm violence to develop models of illegal firearms markets. The charge also called for examining the complex ways in which firearm violence may become embedded in community life and whether firearm-related homicide and suicide become accepted as ways of resolving problems, especially among youth; however, there is a lack of empirical research to address these two issues.
The task of the committee was not to settle all arguments about the causes and cures of violence but rather to evaluate the data and research on firearms injury and violence. Over the past few decades, there have been many studies of the relationship between access to firearms and firearm violence, family and community factors that influence lethal behavior, the extent and value of defensive firearm use, the operation of legal and illegal firearms markets, and the effectiveness of efforts to reduce the harms or increase the benefits of firearm use. We have evaluated these data and studies. In doing so, we have:
Assessed current data bases so as to make clear their strengths and limitations.
Assessed research studies on firearm use and the effect of efforts to reduce unjustified firearm use.
Assessed knowledge of illegal firearms markets.
This report presents the committee’s findings.
GUN CONTROL AND THE SECOND AMENDMENT
Many people reading this report will ask whether the committee favors or opposes gun control, accepts or rejects the right of people to own guns, and endorses or questions the conflicting interpretations of the Second Amendment to the U.S. Constitution (“the right of the people to keep and bear arms shall not be infringed”).
Resolving these issues, though important, is not the task the committee was given. We were asked to evaluate the data and research on firearm violence to see what is known about the causal connection, if any, between firearms on one hand and violence, suicide, and personal defense on the other. In carrying out this task, we have tried to do what scholars are supposed to do—namely, assess the reliability of evidence about the ownership of firearms and discern what, if anything, is known about the connection between firearms and violence. This involves looking at not only how many firearms are owned and who owns them but also the complex personality, social, and circumstantial factors that intervene between a firearm and its use and the effect, if any, of programs designed to reduce the likelihood that a firearm will cause unjustified harm.1 It also includes investigating the effectiveness of firearm use in self-defense. It does not include making judgments about whether individuals should be allowed to possess firearms or whether specific firearm control proposals should be enacted.
Questions of cause-and-effect and more-or-less are not how many Americans think about firearms. Some individuals believe that firearm ownership is a right that flows directly from the Second Amendment or indirectly from every citizen’s right to self-defense. Others believe that there is no right to bear arms, and that firearms play little or no role in self-defense.
These competing beliefs are important and will inform the decisions political leaders have to make. America did not, after all, suddenly become a gun-owning nation. The private possession of weapons has been an important feature of American life throughout its history. But important as these beliefs are, they are not questions that can be easily resolved through scientific inquiry. Committee members have no special qualifications for deciding who has what rights or what the Second Amendment may mean. If the Supreme Court had spoken out clearly on this part of the Bill of Rights, the committee could assume something about what rights, if any, it confers. But the Court has not spoken so clearly. It has allowed Congress, for example, to ban the sale of sawed-off shotguns, but only on the narrow grounds that no one had shown that having a weapon with a barrel less than 18 inches long would contribute to the maintenance of a “well-regulated militia.” And the Court has accepted restrictions on the sale of firearms to felons. But so far, the Court has held that the Second Amendment affects only federal action, presumably leaving states free to act as they wish. (For a review of holdings on the Second Amendment, see Appendix C.)
Our report is not for or against “gun control.” (We put gun control in quotation marks because it is so vague: “gun control” can range from preventing four-year-old children from owning guns to banning their ownership by competent adults.) Knowing how strongly so many Americans feel about firearms and various proposals to control or prevent controls on their ownership, we here state emphatically that our task is to determine what can be learned from existing data and studies that rely on them and to make recommendations about how the knowledge base could be effectively improved. Readers of this report should not be surprised that the committee often concludes that very little can be learned. The committee was not called into being to make policy about firearms. Political officials, responding not only to data and studies but also to widely held (and often passionately opposed) public beliefs, will have to make policy. They should do so, however, with an understanding of what is known and not known about firearms and violence.
SOURCES OF DATA FOR RESEARCH ON FIREARMS VIOLENCE
We may have some advantage, however, in understanding what consequences flow from current levels of firearm availability and from efforts by policy makers to alter those consequences. Or to state our task even more humbly, we may be better than many other people in understanding what the studies of these consequences may mean. A consequence of some action is the concrete, practical reality that is caused by that action. But in the field we address here, many if not most studies of consequences must make do,
not with direct knowledge of the altered reality, but with data that attempt to measure that alteration.
The quality of these data is highly variable. We explain in this report how limited is the knowledge of some of the basic facts. For example, we do not know exactly who owns what kinds of firearms or how the owners use them. Moreover, it may not be easy to improve this knowledge. Asking people whether they own a firearm, what kind it is, and how it is used is difficult because ownership is a controversial matter for one or more of several reasons: some people may own a firearm illegally, some may own it legally but worry that they may use it illegally, and some may react to the intense public controversy about firearm ownership by becoming less (or even more) likely to admit to ownership.
Of course these same problems accompany attempts to measure other behaviors (e.g., illicit use of drugs) and yet ways have been developed to address these problems in those instances (for a review see National Research Council, 2001). While not perfect, many substantial resources have been devoted to addressing the measurement issues that the collection of sensitive data raises. As we discuss in this report, this has not happened in the firearms area, in part, because of the substantial opposition to data collection by interest groups resulting in legal restrictions on collecting information about firearms ownership.2
STANDARDS AND METHODS FOR FIREARMS RESEARCH
All research must follow some basic standards to be accepted by the community of scholars in a field—firearms research is no different. These standards are well known to scientists, although all of them are not achieved in every research effort and meeting these minimal standards does not guarantee that the completed research will be judged to be a contribution to knowledge. These are necessarily minimal standards. Meeting them does not guarantee a piece of research is sufficiently sound to warrant acceptance of its findings. Another National Research Council committee (2002) recently described the scientific process in terms of “six interrelated but not necessarily ordered, principles of inquiry” (pp. 3-5):
Pose significant questions that can be investigated empirically.
Link research to relevant theory.
Use methods that permit direct investigation of the question.
Provide a coherent and explicit chain of reasoning.
Replicate and generalize across studies.
Disclose research to encourage professional scrutiny and critique.
While any group of scholars might modify this list, it poses some commonly accepted standards that our committee used to begin its evaluation of the literature on firearm violence. In so doing we have sought to ensure that often controversial research issues are subjected to these minimum standards for research and to encourage future research in this area to strive for greater rigor.
The committee also noted that certain research strategies are very prevalent in firearms research. These include various interrupted time-series approaches (before-after studies) and the use of case-control techniques. Because these are so frequently utilized in this area of research, we provide an analysis of their use. In Appendix D there is a discussion of the difficulties of before-after type studies, and in Chapter 7 there is one on case-control designs. For advances to be made in firearm violence research, researchers must be careful to use these techniques and approaches with due recognition of their limitations and carefully consider the effect of research design on findings.
In our analysis of the use of these methods in firearms research, we found too often that the conclusions reached require the acceptance of assumptions that are at best implausible. For example, many studies (e.g., Duggan, 2001; Kaplan and Geling, 1998; Kleck and Patterson, 1993; Miller et al., 2002) of the relationship between the access to firearms and firearm violence are conducted with the state as the unit of analysis (a measure of the rate of firearm ownership is correlated with the rate of firearm violence). These results are used to advance the argument that an individual’s probability of access to firearms explains that individual’s probability of committing a violent crime with a weapon. While the problems associated with such cross-level interpretations are well known (the “ecological fallacy”; that is, inferences about individual behavior cannot be drawn from aggregate data about a group; Robinson, 1950), these authors and many who use their work to advance various firearms policies all too frequently draw inferences that cannot be supported by their analysis. Similarly in interrupted-time-series designs, the length of the series and the well-known problems associated with nonexperimental and quasi-experimental designs (see Campbell and Stanley, 1966) are frequently not given the attention required for the work to be judged acceptable. Throughout this report we hold all the research we reviewed to these reasonable standards. Especially in areas of research in which there is much public controversy, it is vital that such standards be maintained.
Using the conventional standards of science, we have reviewed the data and research on firearms and have suggested ways by which these data and studies can be improved. Our readers will judge how well we have done this. We hope they will bring to that assessment the same standards of evidence that we applied in our work.
GUIDE TO THE REPORT
The chapters that follow review and analyze what is known about firearms and violence. Chapter 2 describes the major data sources for research on firearms and violence. This summary assesses the strengths and weaknesses of each system and suggests improvements necessary to make significant advances in understanding the role of firearms in violence. Chapter 3 is a summary of the data describing the extent of firearm violence, firearm ownership, the perpetrators and victims of firearm violence, and the context in which firearm violence occurs. Descriptive in form, it also identifies gaps in understanding of some of the basic facts about the role firearms play in intentional violence. Chapter 4 addresses how criminals and those who use firearms to commit suicide gain access to them. It includes an assessment of various attempts to limit access by everyone and by selected subsets of the population. Chapter 5 assesses the research on the use of firearms to defend against crime, and Chapter 6 examines the impact of laws that facilitate the carrying of weapons.
The committee paid close attention to these issues because they have been central to the recent scholarship on firearms and because they demonstrate many of the difficulties of doing research on firearms and violence. Committee member Joel Horowitz further discusses these issues in Appendix D. Committee member James Q. Wilson has written a dissent that applies to Chapter 6 only (Appendix A), and the committee has written a response (Appendix B).
Chapter 7 considers the role of firearms in suicide. While some of the issues are similar to those encountered in the study of violence, the differences are such that separate attention is required, especially for issues of motivation, firearm acquisition, and lethality. In Chapter 8 we analyze the research on the prevention of firearm violence, reviewing research on the effectiveness of primary, secondary, and tertiary prevention programs. Special attention is given to efforts to prevent gun use by youth. Chapter 9 examines the role criminal justice interventions can play in reducing firearm violence. While many of these efforts are new and have not been adequately evaluated, they are frequently thought to hold promise for immediate impact.