What Cars Can Teach Us About New Policing Technologies

Whitney Curtis for The Washington Post via Getty Images

A traffic stop in St. Louis, Missouri, July 25, 2017

This is not the usual story about cars and freedom: open roads, self-determination, adventure, individualism. The mass production of the automobile transformed twentieth-century America in unexpected and important ways. Foremost, and little-known, it revolutionized policing, spurring the development of police surveillance and increasing individual officers’ discretionary authority. Although this expansion of the state’s power didn’t begin with discriminatory motives, the history of policing drivers makes clear that law enforcement’s surveillance practices haven’t invaded people’s privacy equally, but have reinforced existing inequalities. This is important to remember as contemporary concerns in the face of new technologies abound.

As I explain in my book Policing the Open Road (2019), modern policing developed in response to the challenge of managing all drivers. In the early 1910s, when mass-produced automobiles first appeared on streets originally intended for pedestrians, carriages, carts, and trolleys, they gave new meaning to the word “traffic.” If municipal officials were not dealing with the chaos of gridlock, then they were worrying about automotive speed, which posed dangers to life and limb that prompted comparisons to the recent Great War. One expert, speaking at a 1924 traffic conference at Yale University, claimed that “during the nineteen months of the world war it was estimated that the loss of life by highway traffic accidents in the United States was pretty nearly twice as great as our loss of life through the war itself.” According to the National Safety Council, the death toll from car accidents exploded from 4,200 in 1913 to 29,500 in 1932—a 500 percent increase.

Local governments throughout the country immediately passed a long list of laws regulating the operation of motor vehicles. But they quickly ran into an enforcement problem: everybody violated traffic laws. In the 1920s and 1930s, few assumed that the police would enforce them. Before cars, when private citizens and businesses were the ones who investigated crimes committed against them, most towns and cities had small police departments that, by and large, dealt with those on the margins of society, like vagrants and drunks.

Overseeing the rest of society, the so-called law-abiding citizenry, was largely the task of voluntary associations. Churches enforced moral standards, trade groups managed business relations, civic groups instilled communal spirit, and fraternities and clubs maintained social harmony. The premise of voluntarism was that reasonable, “respectable” citizens would do the right thing out of a sense of decency or shame, reinforced by a watchful community. When individuals could not resolve disputes within these associations, they sued each other for tort or breach of contract. In both associational and common-law governance, the police typically did not get involved.

With the advent of the automobile, injured parties in car accidents continued to sue for tort damages. But not every act of bad or reckless driving resulted in a litigable claim, so it fell on voluntary associations to persuade drivers to obey traffic laws. Church ministers delivered sermons on “Safety Sunday.” Automobile clubs erected safety signs on busy intersections and helped direct traffic. The California Development Association mobilized a “safety pledge” drive, asking motorists to sign a certificate solemnly vowing to “actively practice all safety precautions to the end that the appalling sacrifice of human life and unnecessary suffering caused by carelessness may be stopped.”

Voluntarism, however, proved disastrously inadequate to the task of enforcing norms in the anonymous and rapidly developing new world of automobility. As a result, municipalities expanded their police forces to govern the streets, replacing the social scrutiny of neighbors and the community with that of individual officers. Predictably, many Americans chafed at law enforcement’s meddling in their freedom machines. At the same time, though, most people recognized that they needed to be policed—or, rather, they wanted everybody else to be policed.

Traffic cops soon became regular patrollers on the lookout for more than traffic infractions. In a car society, auto theft became one of the most common crimes. The early decades of the automobile also overlapped with National Prohibition, and bootleggers and moonshiners preferred to move their goods under cover in trucks and cars. Officers realized that while they checked for safety violations, they could also search for alcohol and for telltale signs of a stolen car.

To keep up with these developments in police functions, courts throughout the country modified well-established laws to give officers more search powers. So, too, did the US Supreme Court in the 1925 case Carroll v. United States, which set forth the “automobile exception” that, to this day, allows officers to decide for themselves whether to stop and search a car without first obtaining a warrant from a judge. To justify these expansions of power and to give officers discretionary authority to inspect automobiles, courts pointed to the extensive traffic regulations that undercut drivers’ privacy claims. Ever since the 1920s, judicial opinions have reiterated that individuals have “a lesser expectation of privacy” in their cars whenever rationalizing the police’s actions.


Police surveillance on the streets and highways, however, did not affect all drivers equally. Officers used their discretionary power to treat some as ordinary traffic violators and others as suspected criminals. The former were generally met with courtesy during traffic stops, while the latter were subjected to investigatory searches. Unsurprisingly, the assumptions and prejudices of individual officers informed their conduct. Although police departments didn’t keep statistics on the number of traffic stops by categories like race, a wide range of sources—court cases, law review articles, letters to the NAACP, and even police textbooks—indicate which groups tended to fall under police suspicion.

A 1963 article in the trade magazine Police listed characteristics of people who warranted special scrutiny, including “lone male sitting in car” and “loiterers around public rest rooms,” profiles that targeted gay men. The landmark 1972 case Papachristou v. City of Jacksonville, which overturned centuries-old vagrancy laws and celebrated freedom even in the seemingly mundane acts of wandering and strolling, involved two interracial couples who were arrested—apropos in the automobile age—for “prowling by auto.” Most citizens’ encounters with the police never became a legal case and would have been lost to history if organizations like the NAACP had not kept a record of their stories. In the 1950s, NAACP leaders in Florida, Mississippi, Alabama, and Texas reported a “southwide pattern” of arresting civil rights activists and fining them for minor traffic infractions. In 1956, the president of the Florida branch was beaten and arrested for double-parking his car in front of the local NAACP office. In an automotive society, police harassment of nonconformists, dissenters, and minorities often took place under the guise of enforcing highway safety.

By century’s end, the war on drugs blatantly relied on racial profiling on the highways, known officially by the US Drug Enforcement Agency as “Operation Pipeline” and, more colloquially, as Driving While Black. It is not surprising that many Fourth Amendment cases since the late 1980s involved a car stop of a minority driver for a minor traffic violation. The widespread practice of discriminatory traffic stops has not just contributed to the country’s disproportionate incarceration of black and brown people, but has also violated the dignity and rights of countless innocent citizens unjustifiably subjected to investigatory car searches.

Newer technologies have only bolstered the police’s traffic surveillance capabilities. Computer-equipped patrol cars have now made it possible for officers on the road to check for outstanding warrants and revoked licenses, both of which often stem from unpaid fines or traffic tickets and disproportionately affect poor and minority citizens. A car stop on suspicion for driving with a revoked license is a common enough occurrence that a case challenging its constitutionality is before the Supreme Court this term. Once pulled over, the police, using their discretion, can continue the investigation beyond the initial traffic violation. The odor of marijuana—easy to allege and difficult to disprove later in a court of law—has so often been used to justify car searches that one New York judge declared that the “time has come to reject the canard of marijuana emanating from nearly every vehicle subject to a traffic stop.” Traffic law enforcement was originally intended to protect all citizens, but it has ultimately paved the way for discriminatory policing.


Just as the mass production of the automobile created unprecedented threats to the public sphere, new digital technologies are posing novel dangers. With constant news of data breaches, privacy violations, online harassment, and cybercrime, Americans are increasingly calling for greater regulation of the Information Superhighway, which, in turn, will require enforcement and surveillance.

Consider the proliferation of doxing, fake news, hate speech, and child porn on social media, which can undermine individual security as well as our democracy. Lawyer and sexual-privacy advocate Carrie Goldberg has criticized laws that shield tech companies from liability for what their users post. But calls for Facebook, Twitter, or Grindr to crack down on violent, offensive, and abusive content essentially amount to demands that they monitor everyone who uses their platforms. In short, our well-being depends on some intrusion into each other’s privacy, much as citizen-drivers realized a century ago.

Technological innovation also presents new issues regarding law enforcement that raise difficult questions about the tradeoffs between individual security and privacy. Cameras and drones that offer “persistent surveillance” are touted to reduce crime. DNA testing has the potential to solve cold cases. For example, in the 2012 Supreme Court case Maryland v. King, the defendant was arrested for assault, and when his DNA, collected as part of the routine booking procedure, matched a DNA sample from an unrelated, unsolved rape case from six years prior, he was convicted for that crime. During oral argument, Justice Samuel Alito remarked that the case—the first to challenge DNA collection—was “perhaps the most important criminal procedure case that this Court has heard in decades.” The problem of new technologies is not just about shielding our personal information, but, more than that, about balancing the social benefits of surveillance with its threats to individual privacy.


In striking this balance, we must consider the specific harms to especially vulnerable groups that, in US history, have borne the real costs of surveillance in the name of keeping Americans safe. During the Cold War, for example, the FBI’s COINTELPRO spied on and sought to “neutralize” dissenters from the established political order said to be a threat to American security, such as members of the Communist Party and activists in the civil rights movement, including Martin Luther King, Jr. In more recent echoes of this history, after the terrorist attacks on September 11, the police launched a surveillance program against innocent Muslim New Yorkers based solely on their religion. Some of the strategies included old-fashioned snooping, such as enlisting informants to spy on people, while others involved cameras mounted on light poles aimed at places of worship.

Big data poses another privacy concern, but these dangers do not affect us equally. The life-altering uses of big data are more concrete and dire for those caught in the criminal justice system. More jurisdictions now rely on “risk assessment” programs to determine an individual’s likelihood of recidivism for bail, sentencing, and parole decisions. These programs use algorithms that compile and evaluate all sorts of life facts to try to predict a person’s propensity for crime, and this information is used to determine whether that person gets bail and how long a sentence he or she will serve. Ostensibly color-blind, these algorithms actually rely on factors that not only correlate with race, gender, and class, but also incorporate the criminal justice system’s pervasive biases. Once embedded in computer programs, these biases become much more difficult to challenge than those of human police, prosecutors, and judges. Big data’s potential to threaten liberty is already a dystopian present, not the future, for criminal defendants.

Just as terrifying as the use of technology to forecast a person’s future crimes is the government’s efforts to build a DNA database. Justice Antonin Scalia dissented in Maryland v. King, arguing that gathering DNA samples from felony arrestees—from those who had not yet been charged and convicted of a crime—was a significant intrusion into their privacy. He pointed out that the Supreme Court’s decision was based on the assumption that DNA collection “will not befall thee and me, dear reader, but only those arrested for ‘serious offenses.’” Scalia’s indictment explains why more ink has been spilled over the privacy concerns implicated in consumer genetic testing than over the everyday privacy violations that are a routine feature of the criminal justice system.

Recent reports from Hong Kong not only highlight the dual nature of surveillance, but also provide a cautionary tale. What started in March as demonstrations against an extradition bill have grown into a broader, ongoing protest movement for greater democratic rights. As violence escalated, especially after the police started removing their identification numbers from their uniforms, demonstrators exposed police officers’ identities online as a way to check misconduct. But at the same time, authorities have relied on similar tactics, using facial recognition programs to identify protesters and to arrest leaders of the demonstrations. Surveillance technologies can keep officials accountable, but authoritarian governments can also use them to suppress dissent.

The health of our democracy depends on a vigorous debate about when and how the government can use technology, and these debates must include participation from all parts of society. Take, for instance, facial recognition software, which will, in all likelihood, become a standard feature of police surveillance tools in the United States in the near future. It’s difficult to argue against aiding law enforcement in identifying criminals and exonerating innocent suspects. In fact, many early proponents of using facial recognition software, aside from law enforcement, came from minority and poor neighborhoods that were experiencing rising rates of violent crime. But facial recognition technology encountered significant pushback when it became evident that the software was highly inaccurate in identifying women and people of color. A new bill in New York would prohibit the use of such technology in federally funded public housing, and just this week, California Governor Gavin Newsom signed The Body Camera Accountability Act, which bans facial recognition capabilities on police body cams in California.

The goal of a democratic society should not be to stifle technological innovation, but to constantly reassess how we, as a society, will use these technologies. Under what circumstances can the police use cameras and facial recognition programs responsibly? How can the government ensure our security online without policing free speech? What ought to be the limits on law enforcement’s use of DNA to solve crimes? Which factors can the justice system use to determine pretrial detention, punishment, and probation?

In answering these difficult questions, we must give special attention to the ways that technology has historically and disproportionately affected political dissidents, minorities, and the poor. The history of policing and the automobile suggests that in the hands of human actors, technology tends to replicate the kinds of injustice and inequality that already exist in society. This is precisely why the struggle for equality is crucial to safeguard the privacy and civil rights of all, especially when new technologies are setting up another revolution in policing. In fact, we must treat the two goals as one and the same.

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