Rules of the Road
The Automobile and the Transformation of American Criminal Justice
Spencer Headworth



It is difficult to overstate the automobile’s importance in American society. According to the Census Bureau, over 85% of employed Americans use private automobiles to get to work.1 Motor vehicles are similarly essential means of transportation for family responsibilities, errands, and recreation—to say nothing of the US economy’s dependence on trucking.

Technological innovations, of course, are fundamental to the story of automobiles in America.2 However, the rise of what legal scholar Gregory Shill calls “automobile supremacy”3 owes to much more than the evolution of the internal combustion engine and the emergence of the assembly line system. Economic and business developments were crucial, with manufacturers finding strategies for mass marketing cars and finance companies offering the installment plans that facilitated both mass production and mass marketing.4 From there, a cumulative series of public policy and urban planning decisions cemented private automobiles’ preeminence among modes of transportation.5 Particularly since postwar suburbanization,6 most of the country’s infrastructure for transportation to work, school, and places of worship prioritizes private vehicles. Along the way, law has reinforced automobiles’ status as the top transportation priority,7 entrenching access to a car as a functional necessity for Americans across the socioeconomic spectrum to hold down a job, shop for groceries, care for relatives, participate in politics and civil society, and do most other activities outside their homes.

Thus, as it has to varying degrees elsewhere, automobility has emerged as a defining characteristic of the American socioeconomic system. At a basic level, the term automobility denotes the use of automobiles as a means of transportation. Merriam-Webster dates the word’s first known usage to 1896.8 Scholars point to historian John Burnham’s 1961 article “The Gasoline Tax and the Automobile Revolution” as an early example of the term’s use in academic writing.9 In the early 2000s sociologist John Urry further popularized the term in sole-authored publications and in collaboration with sociologist Mimi Sheller.10 In its more developed academic use, automobility refers to automobiles’ predominance among means of transportation, the various systems and institutions that enable and sustain that predominance, and an accompanying set of attitudes and sensibilities.11

Rules of the Road uses automobility’s prominence in American life as a lens for understanding the past, present, and possible futures of US criminal justice. As the book’s substantive chapters explain, alongside building the world’s foremost car culture, the United States also built the world’s most car-centered criminal justice system. Cars played key roles in the evolution of criminal law, the emergence of modern criminal justice institutions, and the ongoing story of individual rights and systematic inequalities in criminal justice policies and practices.

Cars transformed the lived environment. Governments made unprecedented investments in roads and highways. Planners refashioned existing cities to accommodate automobiles and designed new residential, commercial, and industrial developments around driving. Within only a few decades of automobiles’ introduction to the US market, daily life had come to substantially depend on cars, with driving integral to where Americans lived, what they did for fun, and how they made ends meet.

Through reshaping Americans’ physical surroundings and daily lives, cars also reshaped crime and criminal justice. The proliferation of automobiles foregrounded traffic and its attendant problems as new subjects of regulation, a responsibility that fell to criminal justice authorities. The chaos—and carnage—that the flood of automobiles wrought on city streets constituted a pressing public safety problem and precipitated a new regime of regulation and legal accountability centered on the driving privilege. Cars also directly or indirectly created new crimes—from jaywalking and speeding to auto theft and vehicular homicide—and became prominent means and methods by which people committed preexisting types of crime.

These changes precipitated a fundamental reorganization of criminal justice around the imperatives of a motorized society. In the twentieth century the patrol car and driver emerged as “the basic police technology.”12 The vehicle stop soon became the primary site of direct interaction between the public and criminal justice authorities. Notably, the car-based policing system exposed middle- and upper-class people to unprecedented levels of law enforcement attention. In previous decades police energies were overwhelmingly directed toward poor and marginalized people; the new world of traffic enforcement and vehicle patrol, however, meant that better-off people were far likelier than before to find themselves subjected to law enforcement activity.13 Yet roadside encounters were also a new site where social inequalities manifested, as the massive racial disparities in vehicle stops and associated experiences dramatically demonstrate.14

Readers who have lived in the United States likely have some degree of personal familiarity with the close relationship between cars and the criminal justice system; as either drivers or passengers, most of us have either been pulled over or experienced the concern that we might be. The value of this book’s “car-window view” of US criminal justice, however, goes beyond this personal relatability. Understanding the modern history, current configuration, and foreseeable future of criminal justice requires grasping how myriad car-related cultural, economic, political, and geographic factors have dramatically affected the conceptualization, enactment, and enforcement of criminal law.

With automobility as their common thread, the chapters that follow address multiple key issues and debates in twentieth and twenty-first century criminal justice. As in many aspects of human affairs, priorities and preferences in the administration of criminal law often reduce to choices between competing values. For instance, in the autocentric US criminal justice system, vehicle stops and searches offer a compelling case study of the tension between protecting individual liberties and empowering legal authorities. The Fourth Amendment protects the people against unreasonable searches and seizures. Over the years courts have decided which types of government actions run afoul of this protection and which do not. In Carroll v. United States (1925), the US Supreme Court established the “automobile exception” to search warrant requirements, ruling that vehicle stops necessitate giving officers comparatively wide latitude to conduct searches without obtaining warrants. Moving forward, vehicle stops remained a crucial context for considering the appropriate balance between protecting citizens from arbitrary or overbearing exercises of state power and government’s interest in granting authorities broad discretionary power. These sorts of tensions also manifest in other dimensions of the criminal justice system, for instance, prosecutors’ sweeping discretionary authority in the context of deciding what to charge when impaired drivers cause fatalities.

Relatedly, Rules of the Road addresses the issue of privacy. Surveillance technologies are powerful resources for criminal justice authorities; Rules of the Road examines multiple surveillance methods and their implications for citizens’ privacy. In our autocentric society, prominent examples include GPS location tracking, traffic enforcement cameras, and automated license plate readers. These tools can be immensely helpful in investigating crimes and supporting prosecutions. Yet they also raise significant Fourth Amendment issues and broader questions about the appropriate extent of authorities’ information-gathering power.

In addition to questions about how to best balance authorities’ power and citizens’ rights, Rules of the Road engages multiple dimensions of the wide-ranging discussion about the allocation of criminal justice resources and the most desirable priorities and goals for the criminal justice system to pursue. The modernized police departments that emerged amid the intense motorization of the early twentieth century developed as generalists, with broad authority and diverse responsibilities. Notably, new obligations related to traffic enforcement fell to police departments, a crucial development that shaped law enforcement organizations in the subsequent decades. Debates about what police departments should look like and what police officers should do continue to involve questions about how policing resources should be directed, with traffic duty as a particular point of consideration.

Other dimensions of autocentric criminal justice discussed in this book address similar prescriptive questions about what the criminal justice system should do and how it should do it. Vehicle stops and searches, for example, emerged as a prominent criminal justice tactic during the national prohibition of alcohol and continue to feature prominently in the war on drugs.15 Both Prohibition and the war on drugs offer opportunities to consider the costs and benefits of approaches to intoxicating substances that use criminalization and aggressive enforcement relative to “legalize and regulate” approaches. A conspicuous outcome of the war on drugs is a major increase in incarceration rates; in addition to these more familiar types of criminal punishments, Rules of the Road discusses collateral consequences, that is, penalties that are not part of formal sentences but nevertheless result from criminal proceedings. From the car-window view, driver’s license suspensions connected to non-driving offenses are a particularly impactful version of such consequences.

The car-window view is also useful for thinking through major changes in criminal law and its enforcement. New laws criminalizing intoxicants and policies of aggressively enforcing such measures, often on the nation’s streets and highways, are important examples. More fundamentally, cars themselves changed what cities looked like and patterns of antisocial behavior. Policymakers and officials responded in turn, devising new laws and enforcement strategies that corresponded to the sweeping social changes brought about by automobility. For example, expanded opportunities for criminal activity crossing conventional jurisdictional boundaries engendered an expanded role for the federal government in criminal justice, an area that had typically been state governments’ domain. In an increasingly interconnected country, this “federalization” continued in subsequent decades, especially via the leading role the federal government took in pursuing the war on drugs.

The war on drugs has also contributed heavily to the enormous inequalities in criminal justice system involvement for people of different racial and ethnic backgrounds and social classes. Many readers will be familiar with the huge racial disparities that characterize mass incarceration. Rules of the Road highlights car-related factors that contribute to systemic inequalities in different groups’ exposure to law enforcement attention, criminal charges, and associated penalties. For people who could afford them, automobiles made daily commuting much more feasible, enabling suburbanization. As the twentieth century unfolded, local, state, and federal officials consistently prioritized infrastructure projects focused on cars and their drivers. At the same time, many opportunities to buy suburban homes were difficult or impossible for Americans of color to access. Moreover, urban road-building projects around the country cut through existing neighborhoods, particularly minority neighborhoods, displacing hundreds of thousands and damaging quality of life, property values, and economic opportunity for those who remained. These policy and planning decisions directly contributed to worsening residential racial segregation and structural inequalities. These socioeconomic conditions, in turn, directly contributed to pronounced differences in the rates at which people from different backgrounds are exposed to stops, searches, arrests, criminal charges, and criminal punishments.

As the book describes, vehicle stops are a primary site of racial disparities in criminal justice. These roadside encounters are by far the most common way that people interact directly with police. A prodigious body of research shows that drivers of color, especially African Americans, are disproportionately likely to be pulled over. These motorists are also more likely to experience intrusive elements of vehicle stops, such as intensive questioning, handcuffing, and searches. As Charles Epp, Steven Maynard-Moody, and Donald Haider-Markel compellingly demonstrate, these disparities are driven by police officers’ disproportionate tendency to target drivers of color for investigatory stops.16 In these stops, traffic code violations serve as pretexts to detain and scrutinize selected vehicles and their occupants. Deciding whom to pull over is an exercise of the discretion that characterizes the working lives of law enforcement officers and other street-level bureaucrats,17 including the 911 operators who make pivotal decisions about the allocation of emergency response services.

Given the revenue that citations generate, vehicle stops are also a significant context for considering the role of money in criminal justice policy and practice. In this vein, Rules of the Road explores critiques of automated traffic enforcement that highlight the revenue these systems generate for both governments and the private companies that administer and maintain them. The book also discusses civil asset forfeiture laws, which authorize law enforcement agencies to seize and keep personal property based on officials’ assessment of probable cause to believe that the property in question is connected to illegal activity. On this matter, too, the car-window view is relevant: Most forfeiture actions begin with vehicle stops, and automobiles themselves are frequent forfeiture targets.18 The idea of “policing for profit” in autocentric law enforcement has attracted substantial controversy and stands as one of the numerous contentious topics in contemporary criminal justice.


Rules of the Road proceeds roughly chronologically. It begins around the turn of the twentieth century, in the earliest days of automobile travel in the United States, proceeds through cars’ rise to predominance throughout the twentieth century, and moves on to emergent issues of the twenty-first century. However, each chapter connects the past with the present, emphasizing connections between historical developments and current issues in criminal justice. Along the way, the book attends to how cars shaped American criminal justice and draws on specific car-related contexts to address broader themes and issues. Each of the twelve substantive chapters opens with an introductory “road map”19 laying out its key points. The chapters proceed as follows.

Chapter 1 describes the huge impact that cars had on American society and their key implications for criminal justice. This chapter uses motor vehicle theft as a case study in how lawmakers and law enforcement agencies—as well as other interested parties—reshaped criminal justice in response to the new circumstances of the automobile age. Chapter 2 continues with a discussion of law enforcement agencies’ rapid bureaucratic and technological evolution during the modernization and motorization that characterized the United States in the early twentieth century. When combined with motorized police forces, advances in communication technology—particularly the radio—enabled the centrally coordinated policing systems that we recognize today.

Chapter 3 focuses on a pivotal era for US criminal justice: Prohibition. Efforts to enforce the Volstead Act led to key developments that would shape criminal justice for decades to come, including the rise of vehicle searches and landmark Fourth Amendment rulings from the Supreme Court. As their utility for transporting contraband during Prohibition suggests, automobiles offered historically unprecedented freedom of personal mobility to those who were able to access them. But, as Chapter 4 details, poorer people, racial and ethnic minorities, and women faced significant obstacles and resistance in seeking to avail themselves of the autonomy that cars provided. As jurisdictions adopted driver licensing and examination requirements in the first half of the twentieth century, age emerged as a primary factor in formal determinations of who should be considered fit to drive. Chapter 4 links considerations of age in driver licensing to the broader history of juveniles’ treatment in the criminal legal system, with both contexts demonstrating the evolution of young people’s legal privileges and accountability under the law.

Chapter 5 highlights how cars reshaped American life in the mid-twentieth century. This includes a discussion of the suburbanization that automobile commuting made possible and what it meant for the distribution of resources and opportunities in the country’s metropolitan areas. Vehicle patrol’s corresponding rise to predominance changed the face of policing, driving new debates about the relative merits of foot patrol, vehicle patrol, and other policing strategies. Building on Chapter 5, Chapter 6 focuses on the discretionary decision making that plays key roles in both police rapid response and vehicle patrol. This account notes key court rulings that affirmed police officers’ broad authority to conduct stops and searches based on their own judgment. It also notes the major racial disparities that characterize citizens’ roadside interactions with law enforcement.

Chapter 7 addresses the relationship between the United States’ federalist system of government and a socioeconomic context in which cars—among other factors—have rendered state borders considerably less meaningful. As automobility made interstate crime more feasible, federal authorities took on a larger role in criminal justice. Chapter 7 discusses drug trafficking and human trafficking as two contexts in which interstate activity—and federal involvement—are particularly prominent. These are also both contexts in which moral entrepreneurship campaigns have played important roles. Chapter 8 addresses another such context: drunk driving. This chapter describes the grassroots campaign that fundamentally shifted drunk driving’s treatment in the criminal justice system. It goes on to discuss the role of prosecutorial discretion in contemporary cases involving impaired motorists who cause fatalities.

Chapter 9 engages with the topic of collateral consequences of conviction. In keeping with the book’s theme, it focuses especially on policies that revoke or limit driving privileges as penalties for legal violations unrelated to driving safety concerns. Like many collateral consequences, these policies extend the impact and duration of criminal justice involvement far beyond formal sentences. And, in the case of license suspensions imposed for failures to pay fines and fees, they elevate the role of the criminal justice system as a source of revenue generation. Chapter 10 keys in on revenue generation through criminal justice interventions in the form of civil asset forfeiture. Although seizing property believed to be connected to lawbreaking has a long history, this practice has grown far more commonplace and impactful in the war on drugs. Civil forfeiture proponents argue that the power to seize property is crucial to damaging criminal enterprises and undermining their profitability. Detractors, on the other hand, contend that these policies create undesirable incentives for law enforcement agencies and violate property owners’ due process rights.

Chapter 11 deals with automated traffic enforcement, another area of autocentric law enforcement activity that has attracted controversy related to revenue generation. Many road safety advocates praise the use of camera systems that automatically detect red-light and speeding violations and cite violators. In addition to allegations that these systems chiefly serve to fill government coffers rather than promote safer driving, critics have suggested that automatically generated citations raise due process problems and that these camera networks function as systems of general surveillance. Surveillance and privacy concerns are also central to Chapter 12, which focuses on location tracking in the criminal justice system. Location-tracking technologies are powerful tools for law enforcement officials, particularly in a motorized society. Chapter 12 describes how both radio frequency and GPS trackers have helped authorities keep tabs on people and their vehicles, including the key roles these tools have played in numerous criminal investigations. At the same time, the far-reaching surveillance capabilities that contemporary location-tracking tools provide raise significant issues regarding individual privacy and constitutional protections against government overreach.

The book’s Conclusion opens with a look at two recent happenings: the onset of the COVID-19 pandemic and the 2020 murder of George Floyd and associated protests against police violence and racism. Both events’ implications for criminal justice continue to reverberate, with several notable dimensions directly related to the close connection between cars and the criminal justice system. After recapping some of the book’s main themes, the Conclusion closes with a few notes about what we might expect in the near future of American criminal justice.


1. McKenzie (2015).

2. See Flink (1988) and Heitmann (2018).

3. Shill (2020, 502).

4. Calder (1999); Farber (2002); Olney (1989, 1991); Reyes and Headworth (2022).

5. See Caro (1974).

6. Jackson (1985).

7. Shill (2020).

8. Merriam-Webster, s.v. automobility, (2021).

9. Burnham (1961); Seiler (2008, 4–5); Wells (2012, 300).

10. Sheller and Urry (2000); Urry (2000; 2004).

11. Seiler (2008, 5).

12. Manning (2003, 109).

13. Cressey (1974).

14. Baumgartner et al. (2018); Epp et al. (2014).

15. See Seo (2019).

16. Epp et al. (2014).

17. See Lipsky (2010).

18. See Clemens et al. (2014, 4).

19. Thanks to an anonymous reviewer for suggesting this phrasing.