In 1996, the U.S. Supreme Court legitimized pretextual policing. The case of Whren v. United States began when a vice squad officer noticed a Pathfinder SUV with temporary license plates waiting at a stop sign for more than 20 seconds—an unusually long time to pause at an empty intersection—in what the officer considered a “high drug area” of Washington, D.C. Inside were two young black men. Suspicious, but without any specific reasons that the car’s occupants might be committing a crime, the officer stopped the car for making a right turn without signaling and driving at an “unreasonable” speed. When the officer stepped up to the driver-side window, he saw two plastic bags of crack cocaine in Michael Whren’s hands.

Whren and his friend in the passenger seat appealed their federal drug convictions to the Supreme Court. They argued that pretextual traffic stops violated the Fourth Amendment, which prohibits “unreasonable searches and seizures” and generally requires an articulable suspicion to stop—that is, to make a “seizure” of—an individual. Because the officer did not have legal cause to act on his mere hunch that criminal activity was afoot, he relied on minor traffic violations to investigate.

During oral argument, Justice Sandra Day O’Connor remarked, “I don’t know of any other area that works” like traffic laws, where “sooner or later most of us are going to commit some traffic violation for which we could get a ticket.” The petitioners’ lawyer finished the thought, arguing that laws that everyone violates—thereby making perfect enforcement impossible—gave the police unlimited discretion to enforce them in discriminatory ways.

Pretextual enforcement of the traffic code has been an official strategy in the war on drugs since at least the 1980s. The U.S. Drug Enforcement Agency trained state highway patrols to use such tactics, as did law-enforcement textbooks. Statistics show that police have disproportionately targeted minorities during what is known as “criminal patrol,” a term that reflects the merger of criminal investigations and traffic patrol duties.

The social and legal developments that have led to the systematic policing of minorities, however, did not begin with an intent to do so. The history of discretionary policing, which today enables racialized policing, actually begins with the mass production of the automobile and the practical need to regulate upstanding citizens.

Mass-produced cars rolled off assembly lines around 1910 and took over Main Streets that were originally intended for pedestrians and horse-drawn carriages. Police chiefs throughout the country soon pointed to vehicular traffic and accidents as the biggest problems they faced. To impose order and to ensure public safety, local governments passed long lists of traffic rules and regulations. In addition to speed limits and license requirements, new laws mandated safety equipment, like non-glaring headlights and rearview mirrors. They also coordinated driving norms, for example, by determining who among cars, horses, carriages, and pedestrians had the right of way; and by specifying the speed at which cars could overtake horse-drawn coaches and trolleys. Within a decade, the number of regulations grew exponentially and only continued to multiply.

Extensive traffic codes created an unprecedented enforcement challenge: everybody violated them. That included both drivers and non-drivers, as walking customs became subject to much more regulation when pedestrians had to share the streets with cars. Jaywalking, for instance, entered the lexicon after the mass production of cars. Particularly disturbing was the fact that early motor vehicle owners—traffic violators—were mostly well-to-do. By 1926, a majority of American families owned a car, and it was no less reassuring that this broader population also routinely engaged in law-breaking behavior while on the streets and highways. Officials, experts, and pundits were perturbed that decent Americans would obstinately refuse to follow the rules of the road.

Before cars, the police were few in number and dealt mainly with those on the margins of society, like vagrants and drunks. After cars, the police also had to discipline the respectable citizenry. For the first time, all “law-abiding citizens” (notwithstanding their traffic violations) were subject to policing. From today’s perspective, the democratization of policing may sound preposterous. But this was a consequence of mass automobility. In the American car-dominated society, the traffic stop soon became—and remains today—the “chief point of personal contact between the individual citizen and the law,” as one Yale Law professor put it.

Certainly, the police were also handling more criminal investigations than before, and much of their burgeoning caseload also arose from automobility. The getaway car aided the commission of crimes, especially since law officers could not follow suspects outside their jurisdiction. Until 1934, when the doctrine of hot pursuit entered the common law, fleeing fugitives took advantage of a multi-jurisdictional landscape. Cars also introduced a new crime, auto theft, which became one of the most common crimes in the twentieth century.

But in the federalist United States, where local governments typically handled issues of crime and punishment, criminal mobility did not necessarily lead to bigger police forces and greater police powers. A crime that unfolded over multiple jurisdictions rendered responsibility for the case uncertain, which not only hindered many local prosecutions but also deterred local officials from being more proactive. City or county governments were reluctant to spend money enlarging their police departments to go hunting for criminals who might not fall entirely within their purview.

It also did not make sense for municipalities to spend more money as long as the pursuit and prosecution of crime was largely a private matter. Until the early twentieth century, it was usually citizens themselves who brought charges against those who harmed them or stole from them. Wealthier folks and institutions like banks hired private patrols, detectives, and investigators. Indeed, it was insurance companies that were on the front lines of fighting auto theft.

What finally prompted local governments to invest in more police was traffic law enforcement. The policeman’s duties were to preserve the peace, maintain order, and protect life and property. Mass automobility disturbed peace and order, endangered life, and destroyed property. To manage the fast-growing numbers of “law-abiding” traffic violators, towns and cities throughout the country not only added more manpower, they also strengthened officers’ authority. For instance, in 1924, the National Conference of Street and Highway Safety recommended a new law that made the refusal or failure to comply with any order or direction from a traffic officer a misdemeanor.

These expansions in policing occurred at the state level as well. In 1905, only five states had some form of state police. They were unnecessary when criminal prosecution was a local and private matter, and the idea of centralized police was anathema in the United States. But by the end of the 1930s, almost every state established a police force for the primary purpose of enforcing traffic laws. Officials quickly discovered that while looking for safety violations, patrollers could also look for stolen vehicles and illicit liquor. Traffic and criminal law enforcement began to overlap.

The policing of cars created a conundrum both profound and practical. What did freedom mean in a modern, automotive society that policed all its citizens? And more delicately, how could the police discipline “law-abiding” drivers without antagonizing them? This was especially challenging when it was difficult to tell the difference between criminal suspects and ordinary traffic violators; after all, everybody drove standardized cars. Defendants who challenged police stops and searches of their cars often argued for greater constitutional constraints on police by invoking the interests of “Everyman,” a variant of “law-abiding citizen.” Those who used these seemingly generic labels meant to be all-embracing. But Everyman was hardly a class-, race-, or gender-neutral figure. The term held significance precisely because it conjured a white man from a respectable class who, before cars, had largely been shielded from policing.

The need to regulate drivers and to do so without giving offense necessitated changes to the police function. For one thing, courtesy became a hallmark of professionalized police. In the early years of the automobile, whenever the National Police Journal profiled the achievements of a progressive department, it invariably mentioned how the reforming police chief instilled courtesy in his force.

The mandate that officers act courteously arose most frequently in the context of traffic law enforcement. This association was most explicit in the name of South Dakota’s highway patrol, which was called the “Courtesy Patrol” until 1937, when it was rechristened the “Motor Patrol.” Colorado similarly had the “Highway Courtesy Patrol,” which did not change its name until 1945. Although courtesy emerged from the need to discipline the motoring population, it eventually became a general policy. Many municipal codes, like San Francisco’s, required officers to act “in a courteous manner.” Even if not legally obligated, the Law Enforcement Code of Ethics, published in 1956, obliged officers to “enforce the law courteously.”

It is unlikely that courtesy would have become a badge of police professionalism if respectable citizens were not policed. One indication of this counterfactual comes from the Los Angeles County grand jury in 1932. After receiving numerous complaints, this group of esteemed citizens issued a recommendation to the police department to “make it their business to see that the members of the police force are courteous in their dealings with the citizens”—presumably during a traffic stop, when most of these dealings occurred. But this courtesy, the grand jury report continued, ought not to be extended to “dangerous and known criminals,” but just to “the average citizen.” Implicit in the grand jury’s directive was an instruction to use good judgment, or discretion, to distinguish the respectable from the dangerous.

Scholars and activists today point to discretion as the source of discriminatory policing. That is true. But the early history of policing cars suggests that the initial reason for greater police discretion was to benefit the respectable citizenry.

In fact, white papers and officer training manuals all recommended that the police exercise discretion when directing traffic. One expert insisted that “all traffic violators cannot and should not be handled in exactly the same manner.” It was up to the individual officer to determine how best to proceed in each case, whether it was to ignore the infraction, give a warning, write a citation, or make an arrest. Police consultants advised officers to take the most lenient option or even to decide not to attempt enforcement at all for fear of alienating respectable members of society. If a belligerent traffic cop angered the citizen-driver and aggrieved his or her sense of dignity, that person might, at best, create a public relations headache; at worst, his or her disrespect for law enforcement would undermine the rule of law. Criminal elements did not present this problem; the upright did. Officers thus needed discretion to decide, in the moment, whether a given driver deserved courtesy or not.

Legal changes mirrored the new mandates of courtesy and good judgment. Discretionary policing certainly existed in practice before the advent of the modern motor car, but it did not receive much scrutiny. After cars, police discretion became a recurring constitutional issue under the Fourth Amendment. Because the first moment in a police encounter is a stop, or “seizure,” which could then be followed by a “search,” the guarantee against “unreasonable searches and seizures” has been the main provision governing the police, under both the U.S. Constitution and state constitutions.

Until the early twentieth century, searches and seizures of “persons, houses, papers, and effects,” as listed in the Fourth Amendment, required a warrant. There were well-established exceptions, but the warrant requirement was the general rule. Cars should have fallen under the category of “effects.” But state courts throughout the country, and the Supreme Court in the 1925 case Carroll v. United States, created what is now called the “automobile exception,” which permits officers to stop a car without a warrant if they have reasonable or probable cause to believe it was transporting contraband, which was liquor in most cases during the Prohibition era of the 1920s. Not requiring warrants but still requiring probable cause seemed like an appropriate compromise between the needs of law enforcement and the rights of citizen-drivers.

By setting aside the warrant requirement, however, courts sanctioned police discretion, for the individual officer, rather than a neutral magistrate, would decide in the first instance whether to search a car or to allow the driver to go on his or her way without further ado. As courts were wont to point out when reviewing police action, the Fourth Amendment did not prohibit warrantless searches and seizures, but only those that were “unreasonable.” Over the twentieth century, as the United States became an automotive society, Fourth Amendment jurisprudence shifted emphasis from a question of warrants to a question of reasonableness, which centered on the police’s exercise of discretion.

Was it reasonable for an officer to force a car into a roadside ditch based only on the driver’s reputation as a rum runner? Was it reasonable to arrest a suspected bootlegger for passing in a no-passing zone and then to search the trunk of his seized car? Was it reasonable to search inside the pockets of a jacket left on the backseat of a car? Was it reasonable to search containers found inside the pockets of an overcoat worn by a driver arrested for driving with a revoked license? Was it reasonable for an officer to ask drivers where they were coming from and where they were going for any reason or no reason at all?

As Fourth Amendment cases proliferated, reflecting the welter of life that confronted police officers, the rules of decision became increasingly fact-based, complex, and inconsistent. One law professor pointedly called this area of law an “embarrassment,” while another declared that it was “in tatters.” It was not easy for judges, including Supreme Court justices, to pin down a definition of reasonable policing, let alone to flesh out a coherent theory for determining reasonableness. It proved difficult for judges to second-guess the police’s exercise of discretion when it was the guilty, not the innocent, who raised Fourth Amendment challenges. All the more so when the nature of police work often involved split-second decisionmaking in uncertain circumstances.

This was especially true when patrolling the byways and highways. Law enforcement advocates argued that traffic stops were “one of the most dangerous aspects of police work” because officers, when approaching a car, exposed themselves to an unknown situation. Their argument carried the weight of experience that judges did not share. Law enforcement advocates soon learned to marshal the exigencies of traffic stops to justify greater police powers even when the legal question at issue did not pertain to cars. In the twentieth-century United States, policing the automobile had become synonymous with policing American society.

In case after case, courts concluded that the police had acted reasonably. As a leading Fourth Amendment scholar explained, the reasonableness standard essentially meant that “appellate courts defer to trial courts and trial courts defer to the police.” Every now and then, an individual defendant won. But more often, reasonableness functioned as a deferential standard, which then migrated to other areas of law as well. An early 1970s textbook explained that the “system of criminal justice abundantly provides for broad use of discretion by its law enforcement officers.” In support, it pointed to “specific sections of the criminal codes” that incorporated police discretion through the word “reasonable.”

This brings us back to Whren v. United States. It was reasonable, according to the Supreme Court, for the police to use a minor traffic violation as a way to look for drugs. According to the unanimous opinion, “the Fourth Amendment’s concern with ‘reasonableness’ allows certain actions to be taken in certain circumstances, whatever the subjective intent” of the officer. Those circumstances included a car stop for a traffic violation, which any officer with a modicum of patience will eventually observe of almost any driver. For all nine justices, it seemed untenable to hold that enforcement of a valid law could violate the Fourth Amendment, even if motivated by pretextual reasons.

Whren was just one of many cases that began with a minor traffic violation and ended with a drug conviction. “Criminal patrol” has indeed been an effective law-enforcement strategy in the war on drugs, which has been waged mostly against racial minorities. But what made “criminal patrol” possible is the combination of too many traffic laws and constitutional deference to police discretion. Both developments had their origins in the need to govern Americans on the road.

This history had far-reaching consequences on the meaning of freedom. When American society turned to the police to maintain highway safety and order, the defense of liberty was not simply about restraining the police’s power. The challenge, as Policing the Open Road makes clear, was to figure out how to incorporate policing within the meaning of freedom itself.

I am grateful for the opportunity to respond to Sarah A. Seo’s excellent take on Whren v. United States (1996), a dismaying case that speaks volumes about the Supreme Court’s abdication of its duty to fully enforce constitutional limits on government power. As discussed below, Whren is not just an affront to the values underlying the Fourth Amendment (though it certainly is that), but also a vivid manifestation of the “deferential standard” that has spread like a disease throughout the Court’s constitutional jurisprudence, resulting in its endorsement of a federal Leviathan that would have horrified the Founders and the habitual rubber-stamping of arbitrary infringements on liberty by government at all levels. Thus, Whren is a kind of constitutional microcosm: what it allows police to do to the Fourth Amendment specifically, the Supreme Court frequently allows government to do to the Constitution generally.

Professor Seo notes that Whren was the case in which the Supreme Court “legitimized pretextual policing.” She’s right, and it’s vital to understand precisely what that entails. It is well-known that America’s criminal justice system features massive and widespread racial disparities. Those disparities include everything from the frequency of traffic stops and vehicle searches to the quality of plea offers and the length of prison sentences. Another practice that appears to be widespread is racial profiling, which includes targeting motorists for “driving while black.” As Radley Balko relates in a Washington Post piece exhaustively documenting racial disparities in our criminal justice system, “there is a running joke in law enforcement when it comes to racial profiling: It never happens … and it works.” But what, if anything, judges should do about it is an important question, and it was that question the Supreme Court confronted in Whren.

As Professor Seo recounts, the defendants in Whren were two young black men who were pulled over by plainclothes detectives in Washington, D.C., ostensibly for making an unsignaled turn and then taking off at an “unreasonable speed.” The detectives found crack cocaine in the car, and the driver and passenger were charged with federal drug felonies carrying significant prison time. The defendants invoked the Fourth Amendment’s exclusionary rule on the grounds that the traffic stop was pretextual and would not have been undertaken but for the officers’ desire to look inside the car and investigate their hunch that it might contain drugs. Their contention about the pretextual nature of the stop was bolstered by the fact that the plainclothes detectives who made the stop were part of a special vice squad whose members were specifically forbidden by department regulations from enforcing traffic laws unless they observed a violation “‘so grave as to pose an immediate threat to the safety of others.’”

But the Supreme Court rejected the Fourth Amendment challenge and held that it was irrelevant whether the defendants had been targets of racial profiling because the Court’s precedents “foreclose any argument that the constitutional reasonableness of traffic stops depends on the actual motivations of the individual officers involved.”

As the kids say these days, Wait—what?

Yes, you read that right. According to the unanimous Supreme Court, “the Fourth Amendment’s concern with ‘reasonableness’ allows certain actions to be taken in certain circumstances, whatever the [officers’] subjective intent.”

To fully appreciate the implications of that remarkable assertion, let’s hypothesize a perfectly candid officer, or “PCO,” who works for a department that tolerates (or perhaps even tacitly encourages) racial profiling. We can imagine the following exchange with defense counsel (DC) during a suppression hearing:

DC: You were working undercover at the time you stopped my client for failing to use his turn signal, correct?

PCO: That’s correct.

DC: And you were specifically forbidden by department regulations from initiating any traffic stops except in cases of immediate danger to others, is that right?

PCO: Correct.

DC: You didn’t think an unsignaled turn represented an immediate danger to others, did you?

PCO: No, I did not.

DC: So how long had you been following Mr. Doe before you made the traffic stop in specific violation of department regulations?

PCO: I don’t know exactly [checks notes]—for a few minutes at least.

DC: And why were you following him?

PCO: Because I wanted to pull him over and look inside his car, and I was waiting for him to commit a traffic violation so I could initiate the stop.

DC: Why did you want to look inside his car?

PCO: Because he’s a young black guy driving an expensive SUV in a certain part of town at night, and to me that adds up to drugs in the car.

DC: So you admit you were engaged in racial profiling?

PCO: Absolutely.

DC: And to be clear, you would not have started following my client but for the fact that he was a young black guy driving a nice car, correct?

PCO: Correct.

DC: Nor would you have initiated the traffic stop but for the fact that my client was black, is that right?

PCO: Yes, that’s 100% accurate.

So to summarize, the hypothetically candid police officer has admitted to violating the defendant’s civil rights by engaging in illegal racial profiling, and he has acknowledged that he would not have made the stop but for the driver’s race, which is a federal crime. Nevertheless, the Supreme Court would find no Fourth Amendment violation here because under Whren, the only thing that matters is whether there was a legitimate reason why the police could have stopped the car (in this case, failure to signal a turn)—regardless of why they actually did make the stop.

Indeed, far from denying that the detectives may have acted unlawfully in Whren, the Supreme Court expressly acknowledges that possibility, but then blithely asserts that the constitutional basis for objecting to the intentionally discriminatory application of laws is “the Equal Protection Clause, not the Fourth Amendment.” In other words, a traffic stop that constitutes both an equal-protection violation and a criminal act on the part of the police may nevertheless be “reasonable” for Fourth Amendment purposes, according to the unanimous Supreme Court in Whren.

That is, of course, preposterous. But such is the state of Fourth Amendment jurisprudence today—and of many other constitutional provisions whose government-limiting substance has been sapped by generations of deference-venerating judges.

And lest we suppose the Supreme Court’s breathtaking abdication in Whren will have only limited or sporadic real-world consequences, Professor Seo reminds us that “pretextual enforcement of the traffic code has been an official strategy in the war on drugs since at least the 1980s,” and in fact the Drug Enforcement Administration has “trained state highway patrols to use such tactics” in support of the so-called “‘criminal patrol,’ a term that reflects the merger of criminal investigations and traffic patrol duties.”

Honestly, it’s hard to say which is more dismaying: the continued use of racial profiling by law enforcement agencies that were supposed to have evolved as part of the “new professionalism,” or the judiciary’s persistent indifference to the fact that the ability to fully enjoy Fourth Amendment rights while driving a car in America still turns in significant measure upon the color of one’s skin and the discretion of those who patrol our nation’s roads.

Sarah Seo’s lead essay provides a compelling account of the automobile’s outsized role in the development of Fourth Amendment search and seizure jurisprudence, as well as the erosion of the Fourth Amendment’s protections on the open road. Her chronicling of the imperative to police “law-abiding citizens” in the wake of an expanded traffic code and the resulting rise of police discretion and courtesy is similarly persuasive and well-reasoned. At times, however, she asks the automobile to drive too many of these developments in policing and Fourth Amendment jurisprudence.

One of the essay’s more valuable contributions is its portrayal of how the exceptional nature of the automobile created situations in which “traffic and criminal law enforcement began to overlap.” To contemporary readers, this may seem like an especially unremarkable point—why wouldn’t traffic enforcers also pursue unrelated felonies? But when it comes to the enforcement of civil ordinances, this is hardly the norm. For example, we do not expect health inspectors to turn into murder investigators simply because they find a body in a restaurant, or building inspectors to pursue an armed robbery after they discover a firearm on a construction site. It is only the car, with its intrinsic mobility, that combines such broad civil and criminal enforcement powers in a single government official.

As Seo notes, the incorporation of these new responsibilities and the attendant need to discipline “law-abiding” citizens necessitated a revolution in police discretion and courtesy. Yet her argument neglects to fully acknowledge an important aspect of this evolution: the noncriminal, relatively minor nature of most traffic offenses. Traffic codes altered not just whom the police were interacting with, but why. The first part—the whom—explains why police were so quick to embrace discretionary and courteous policing. As Seo explains, traffic stops risked alienating the “respectable members of society.” No doubt the chance for that “respectable member of society” to benefit from a little discretion from a courteous police officer explains much of the public’s support of the practice. But I would suggest that mere prospective self-interest does not tell the whole story.

After all, while hearing about a bedraggled motorist getting off with a warning usually elicits little more than a collective shrug, few have so tepid a response when police discretion manifests as looking the other way on a rape or murder—no matter how upstanding the citizen involved may be. Likewise, even well after the rise of the automobile and “courteous” policing, the public regularly ignored the roughing up of criminal suspects. As Seo notes, much of this can be attributed to a willingness to “other” a supposed underclass of criminals. Yet the vitriol pointed at even some first-time or otherwise “respectable” offenders suggests that this does not fully explain how the public’s hunger for retribution can still overcome its desire for courtesy in more serious circumstances. Thus, while the “who” at the heart of traffic stops may have provided the incentive for discretion and courtesy, it was the “why” behind these stops—a minor and largely innocuous offense—that made that discretion appear benign and courtesy proper.

Furthermore, if we want the complete picture of the public’s relationship with police discretion, we need to dive into the practice’s darker side—as a source of targeting—just as deeply as its potential to reduce enforcement. Seo skillfully describes how the combination of traffic codes, which turned the entire motoring public into scofflaws, and automobiles, which made the pre-stop identification of those motorists practically impossible, forced discretion to act as a form of leniency. As such, the automobile can rightly claim the lion’s share of the credit for incorporating this gentler type of discretion into modern policing. But her reliance on the automobile to drive the narrative around pretextual policing means that her essay omits a key factor in the history of police use of discretion as a targeting mechanism. Any story of police discretion as a form of targeting must pay greater homage to the pedestrian.

Indeed, a discussion of police discretion without the phrase “stop-and-frisk” feels oddly empty. Whereas in traffic stops, the legal basis of the stop often precedes the identification of the motorist, in the pedestrian arena, the reverse is true. With more information about the race, gender, and general appearance of an individual prior to any pedestrian stop than before most traffic stops, the police officer invariably does more screening of what kind of person to stop in the first place. All too often, this has meant the kind of discriminatory policing to which Seo alludes in her description of “criminal patrols.”

In 1968, the U.S. Supreme Court supercharged this discretion and its propensity for abuse in Terry v. Ohio by pushing Fourth Amendment search-and-seizure jurisprudence onto a sliding scale. Prior to Terry, there was generally only one type of police stop, which required, if not a warrant, at least probable cause of wrongdoing. Searches faced similar constraints. Terry, however, created the concept of an investigatory stop, which could begin with only reasonable suspicion and evolve based on additional information generated as the stop persisted. This lowered the bar for stops and searches, thereby increasing the breadth of officer discretion even further.

In one way, the kind of discretion enabled by Terry and its progeny may be even more problematic than that which originated in the traffic context. How can this be, given that a voluminous traffic code has combined with a deferential holding in Whren v. United States to make nearly every motorist susceptible to a pretextual stop? Because, however flimsy the rationale provided by a traffic violation, at least it represents “enforcement of a valid law” set out by a duly elected or otherwise democratically accountable body. Pedestrian stops, on the other hand, usually rely solely on an unelected police officer’s judgment that a perfectly legal series of actions nevertheless justified a stop.

The same courts falling over themselves to find all manner of traffic related actions “reasonable” and therefore sufficient to support a stop have done the same sort of mental gymnastics to uphold all manner of stop-and-frisk situations. Making ill-defined “furtive movements,” exhibiting nervousness—or unusual calm—and being present in or leaving a given area have all helped provide the basis for these stops and subsequent searches. As Seo observes, Justice O’Connor was surely correct that “sooner or later most of us are going to commit some traffic violation for which we could get a ticket.” But by that same token, sooner or later, most of us are going to commit enough otherwise innocent actions to provide grounds for reasonable suspicion.

Seo concludes by stating that “what made ‘criminal patrol’ possible is the combination of too many traffic laws and constitutional deference to police discretion.” These pedestrian stop cases suggest that this is only half-right. Although too many traffic laws and the mobility of automobiles helped to accelerate the line of court cases that created so much deference to police discretion, there is ample reason to believe that this trend would have occurred without either. Pedestrian stops underwent a parallel, and at times interconnected, development. The test for “reasonableness” in both instances was the same; the courts simply traded traffic codes for dubious officer judgments and suspect mobility for possible officer danger. Neither of these factors is unique to pedestrians, and courts have frequently turned to these kinds of Terry factors to justify all manner of automobile stops as “reasonable.”

So, did cars drive these developments relating to police and freedom? For the most part, yes, they did. But did they have to? No, probably not. As in real life, we likely would have reached the same destination on foot—it just would have taken longer to get there.

I am pleased to have this chance to share some thoughts on Sarah Seo’s new book, Policing the Open Road, about the relationship between our car-centered culture and policing. The fascinating historical story she tells—how the introduction of the mass-produced car, which seems so unrelated to criminal justice, led to fundamental changes in policing—alone makes her introductory essay worth reading. Like: why are the police trained to be polite? Because when they started policing roads, they suddenly came into contract with middle- and upper-class citizens, and their prior gruffness was no longer acceptable.

Perhaps more important, Seo’s book is part of a critical refocusing of our discussion of criminal justice reform, away from mass incarceration (where I spend most of my time) and towards mass punishment. Most reform discussions focus on prisons, and prison populations are the central metric by which we compare ourselves to other countries and our own past. But prisons, and the generally serious offenses that send people there, are just the tip of the punishment iceberg. While there are about 1.4 million people in prison, we send over 10 million to jails every year, and we make about 10 or 11 million arrests—most of which are for offenses that will never send someone to prison (only about 500,000 are for serious violence and 1.3 million for serious property crimes).

In other words, while our reform efforts tend to focus on felonies and prisons—on incarceration—almost everyone’s contact with criminal justice is through the far vaster, far more invisible, and far more disorganized world of Misdemeanorland (to steal Issa Kohler-Hausmann’s fantastic neologism). And as people like Kohler-Hausmann and Alexandra Natapoff (in her Punishment Without Crime) have recently shown, the overall impact of Misdemeanorland surely dwarfs that of the felony system, even if it receives only a fraction of the attention. Seo’s examination of policing automobiles is an important contribution to this, since she is looking at the single most common form of police-citizen interaction (at least for those who do not live in a small subset of heavily policed urban neighborhoods), and one of the few that easily and frequently crosses the lines of race and class.

In fact, it was this universality of traffic stops that jumped out at me, leading first to one troubling observation and then to one troubling question.

To start, Seo’s account complicates some aspects of the narrative we rely on to explain why our system is so punitive, especially at the misdemeanor level. Oftentimes discussions about criminal justice reform turn to the issue of “overcriminalization,” the idea that we criminalize too much conduct that should not be a crime in the first place. By and large, this is somewhat of a red herring in the context of felonies and prison populations; even if many of the people in prison need not be there (or be there for as long), almost all have often been convicted of conduct we all agree should remain criminalized (like assault or theft). But it is not a minor point when we get to Misdemeanorland.

Misdemeanorland is defined by overcriminalization. We have criminalized as misdemeanors all sorts of conduct that is unappealing and problematic but almost certainly not deserving of any sort of criminal punishment, like jaywalking, spitting on the street—or even non-reckless speeding. And even when the conduct these low-level laws target may seem criminally problematic, the laws are often drafted so broadly that they cover all sorts of behavior they surely shouldn’t.

Most discussions of this overcriminalization of Misdemeanorland frame it as the logical end-result of America’s deep-seated racism and classism. We quickly turn to Misdemeanorland to handle things like speeding or playing loud music because of an almost instinctive desire to punish the poor, people of color, and especially poor people of color, a response that crowds out less punitive ways to address these issues.

That instinct is no doubt significant, but Seo’s account introduces an important wrinkle to this take.

When states first stated regulating driving, the people driving were far more likely to be middle- or upper-class and white—they very people we think (correctly) that the system goes out of its way to treat better. Yet even here, our instinct was to regulate driving primarily through the criminal code and police enforcement. As Seo points out, the rise of the car led to wealthier Americans suddenly having encounters with the (rapidly expanding) police, not with local and state governments coming up with new non-police ways to regulate driving. And the statutory responses were often punitive as well. In Georgia, for example, every traffic violation is a misdemeanor carrying not only the risk of a fine but of jail time.

Now, to be absolutely clear, if wealthier white Americans and their families and friends were repeatedly subjected to the indignities of our massive misdemeanor system—arrested and cuffed in public, shipped off to Rikers for a few days, and then saddled with fines and fees and restrictions on liberty for nothing more than, say, crossing in the middle of the street or driving without a seatbelt on—we would surely see a massive push for changes, and Misdemeanorland would not be nearly as invisible to most people as it is.

But Seo’s historical account points out just how deeply held our punitive instinct is. It is an instinct that has waxed and waned, to be sure—our incarceration rates have been much lower in the past, even when national politics were surely more punitive—but Seo’s story of cars and policing and driving misdemeanors is an important reminder of just how broad that instinct can be.

Seo’s discussion of the normalcy of traffic stops also brought up for me an intriguing question about policing reform. While there is a broad bipartisan consensus for prison reform, such is not the case for policing, and I wonder if traffic policing, and the civility-in-policing norms it created, is one reason why. Despite new data about the remarkable number of Americans who know someone who has had at least some contact with prisons or jails, those two institutions remain generally alien to most people. When we hear that conditions are awful or abusive, many if not most voters do not filter that information through any personal experience.

Such is not the case, however, for policing. Far more people have had interactions with the police than with prison or jail, and most of those interactions have been via traffic stops—stops where the police, as Seo points out, have been trained to be more polite. So when people otherwise uninvolved with the criminal justice system hear about police brutality, aggressiveness, and harassment, they have personal experiences to turn to—experiences that do not line up with those accounts. “Well, all my interactions with the police have been polite and respectful” might be anecdotal reasoning, but it is often compelling anecdotal reasoning.

Obviously the solution isn’t to encourage police to be less civil when stopping suburban motorists. But by highlighting the unique ubiquity of police vehicle stops, Seo may have also shed light on why efforts to reform policing seem to face more of an upward battle than those to fix other aspects of our flawed criminal justice system.

I am grateful for the thought-provoking responses from Clark Neily, Lars Trautman, and John Pfaff. It is a privilege for a historian to engage with experts working on real-world issues, so I’ve been looking forward to this conversation.

A common theme in the three response essays is the surprise of reading a history of criminal justice from the perspective of Everyman, or the “law-abiding citizen.” While there are many unexpected turns in this history, one aspect that may not be too surprising is that when government officials were dealing with respectable folks, the punitive instinct took time to develop.

Policing was not a widespread mode of governing American society before cars. True, police officers disciplined drunks and vagrants. But everybody else was self-regulated through the common law and voluntary associations like churches and trade unions. Chapter 1 of my book Policing the Open Road describes the strange, sometimes comical, attempts to persuade citizen-drivers to follow the rules of the road by appealing to their honor and reasonableness.

Only after officials and policymakers resigned themselves to the fact that such appeals were insufficient did they supplement traffic law enforcement with criminal punishment. It was the incorrigibility of law-abiding citizens that made the punitive response necessary as a last-resort. Because so many people drove—a majority of families had a car by the mid-1920s—and because every town and city in the country had to deal with the sudden ubiquity of cars, the automobile rendered nineteenth-century self-regulation inadequate and ushered in twentieth-century police governance.

Just how much of this shift was about cars? And, as Lars Trautman asks, where does the practice of stop-and-frisk fit into this story? Even before cars, the police harassed people if they looked out of place. But cars completely changed the historical trajectory of this practice in two ways.

First, traffic policing led to much more policing generally. To use Los Angeles as an example, between 1902 and 1912, the ratio of patrolmen to residents increased by a third. During the same period, traffic arrests went up by over twentyfold, and order-maintenance types of offenses (begging, drunkenness, disturbing the peace, and vagrancy) increased by 45 percent.

Confirming the causation between cars and routine policing, the Los Angeles Police Department reported in 1912 that while the largest task of the traffic squad—which they discovered was “practically self-supporting” from the fines it collected—was to direct traffic, it also “assisted in the general work of the Police Department.” In other words, the need to manage traffic led to more police officers, who then were able to do more police work.

Second, although cars did not precede the existence of police discretion, the policing of “law-abiding” lawbreakers did make it visible as a legal issue. Consider this counterfactual: what would the history of stop-and-frisks look like if the police did not bother respectable people? I submit that the practice would have stayed under the radar.

Here’s why: Terry v. Ohio was decided in 1968, which came pretty late in the social and legal history of stop-and-frisks. Back in the 1930s and 40s, progressive legal reformers had tried to legalize stop-and-frisks. Under the common law, stop-and-frisks were illegal without a valid arrest based on probable cause. The unlawful practice had not been controversial and rarely received the attention of judges and law professors—until cops began to stop and frisk respectable people. Reformers believed that legalization would allay any hard feelings that an innocent person might harbor, while also allowing the police to continue stopping and frisking criminal suspects.

Ultimately, the Terry rule adopted the earlier proposals; the opinion even cited them. The Warren Court attempted to strike a balance between individual rights and law enforcement needs by requiring reasonable suspicion. It was a lower standard than probable cause, but at least it was more than mere suspicion, the standard that the state of Ohio had sought.

To create an entirely new category of searches and seizures that did not require probable cause, both Chief Justice Warren and the earlier reformers cited Carroll v. United States. That’s right—the 1925 case that established the automobile exception, and the very first time that the Court created a new category of searches and seizures that did not require warrants.

Chapter 3 of Policing the Open Road tells the history from Carroll to Terry in more detail. The point that I want to emphasize here is to confirm Trautman’s observation that the “same courts falling over themselves to find all manner of traffic related actions ‘reasonable’ and therefore sufficient to support a stop have done the same sort of mental gymnastics to uphold all manner of stop-and-frisk situations.”

I would go even further to say that cases on the police’s authority to stop and search a person or a car were mutually reinforcing. Carroll provided precedent for Terry, which, in turn, provided precedent for later car cases. In fact, the first case to “give some flesh to the bones of Terry” involved the frisk of a person sitting in a parked car. In the car-dominated United States, the law on policing cars specifically, and the law on policing generally, built on each other.

Policing the Open Road explains how the history of policing Every Driver ended with Driving While Black. Neily’s criticism of Whren v. United States is not only spot-on, it describes the problem more incisively than my initial essay suggests. It’s troubling that under the Supreme Court’s interpretation, the Fourth Amendment countenances pretextual policing and racial profiling. So what is surprising is that the decision was unanimous. What explains the Supreme Court’s consensus on this injustice?

The Whren opinion itself eliminated one possible explanation. Before Whren was decided, several lower courts had cited the challenges of proving that an officer had ulterior motives for stopping a car. But the Court specifically disclaimed evidentiary difficulties as a basis for its ruling.

I suspect that the answer lies in a concern that “traffic law exceptionalism” could end up undermining the rule of law.

As Justice O’Connor remarked, “I don’t know of any other area” of law where “sooner or later most of us are going to commit some traffic violation.” If everybody violates the traffic code, then its enforcement must, by necessity, be selective. This may seem troubling. But selective enforcement alone does not pose a constitutional problem. Police agencies have to prioritize which laws to enforce because of the reality that their resources are limited.

Whren’s lawyer argued, however, that traffic laws are “unique.” There are so many rules and regulations that police officers effectively exercise unrestrained discretion, the very definition of arbitrary power.

But if the Court were to permit a criminal defendant to claim a Fourth Amendment violation based on a pretextual speeding ticket, then a driver could challenge a valid speeding ticket based on pretext—a scenario that several justices mentioned during oral argument. The resulting state of affairs would wreak havoc on traffic-law enforcement and public safety on the streets and highways.

And although traffic laws seem special in how normal and frequent violations are, traffic lawbreaking is arguably an extreme example of a common phenomenon in the modern United States. There are many laws, rules, and regulations that are routinely ignored by both citizens and their enforcers.

The problem, then, is determining “at what point a code of law becomes so expansive and so commonly violated that infraction itself can no longer be the ordinary measure of the lawfulness of enforcement,” as the Whren opinion put it. Today the challenge might involve traffic laws, but the next case might be about the Clean Water Act, and so on. And if the Court were to get in the business of reviewing when valid laws are effectively repealed by widespread lawbreaking—to the point of punishing the police for enforcing those laws—then the rule of law would be turned upside-down.

But what is different about traffic laws from, say, the Clean Water Act, is the racial tilt of criminal patrol. One way of drawing the line between lawful and unlawful enforcement of the laws that everyone violates is to maintain that racially discriminatory enforcement is unconstitutional. This was precisely Whren’s argument, which the Court rejected—at least under the Fourth Amendment. According to Whren, claims of unequal enforcement must be brought under the Fourteenth Amendment’s Equal Protection Clause.

This seems fair enough, and perhaps even the liberal justices signed on to Whren because minority defendants may at least have an equal protection claim.

But there are still two reasons to rue the Court’s decision. First, the very same year that it decided Whren, the Court also decided United States v. Armstrong, which set forth what criminal defendants must do when trying to make a selective prosecution claim on the basis of race. To put it simply, Armstrong made it nearly impossible to do so.

Second, whether one thinks about the overpolicing of minorities as a Fourth Amendment issue or an equal protection issue makes a difference. Viewing this primarily as a discrimination problem, rather than as a problem of policing itself, obscures an important normative question about how much power the police should have in a free and democratic society. Should the police be able to search a car during a routine traffic stop? Should it be possible for minor traffic violations to lead to an unrelated criminal investigation? Unfortunately, these are not the questions that are asked when arguing that minority Americans are not treated the same as “Everyman.”

Finally, John Pfaff ended his response essay with the troubling thought that police reform may face an uphill battle because “when people otherwise uninvolved with the criminal justice system hear about police brutality, aggressiveness, and harassment, they have personal experiences to turn to—experiences that do not line up with those accounts.” I agree wholeheartedly that this is a hurdle. My hope for Policing the Open Road is that readers will never stop asking how our policies and laws would change if the overpolicing of cars happened to us all.

I am thankful for Clark Neily’s deep dive into the intricacies of Whren vs. United States, in part because it allows me to step into the unusual position of defending aspects of a Supreme Court decision upholding far-reaching police authority. While I share Neily’s dismay over the pretextual policing practices at the heart of Whren, I cannot agree that the Supreme Court committed a “breathtaking abdication in Whren.”

How can I possibly reach this conclusion given my own trepidations about the kind of expansive police authority enshrined in Terry v. Ohio? It all comes down to the Court’s deference. More specifically, deference to whom.

In Whren, that deference was to the source of the traffic code: a legislative body. No doubt, that code has run amok, now capturing so much activity of dubious significance as to render nearly every motorist a violator in the long run. But each of those infractions relates to the enforcement of a valid law. The proliferation of those laws does not render any given one moot nor deputize the Court to rein them in selectively in criminal proceedings.

Justice Scalia made exactly this point in Whren: “[W]e are aware of no principle that would allow us to decide at what point a code of law becomes so expansive and so commonly violated that infraction itself can no longer be the ordinary measure of the lawfulness of enforcement. And even if we could identify such exorbitant codes, we do not know by what standard (or what right) we would decide, as petitioners would have us do, which particular provisions are sufficiently important to merit enforcement.”

Pretextual policing is a persistent, significant, and odious problem. All of that makes the lure of a seemingly quick judicial fix especially appealing. But do we really want to empower such wide-ranging judicial activism? Are these not ultimately policy questions better suited for a different organ of government, or at least considered by a court in a more fitting venue than a criminal motion hearing?

Just consider what a court would need to do to resolve a motion based on pretext. One option would be to delve into an individual officer’s motives for the stop in question. Under the assumption that the hypothetical “perfectly candid officer” would remain exactly that in most cases—purely hypothetical—the court would have to turn to other observable displays of pretextual intent. What would these look like, and how, moving forward, could you stop minor alterations to police practices from easily obfuscating these indicators of motive?

So perhaps the court looks instead at an officer’s prior pattern of behavior, or that of his department. But divining pretext based on past actions is a probabilistic endeavor that is somewhat anomalous to criminal procedure—requiring every local trial court judge to become a statistics expert is a recipe for inconsistent decisions and outright errors. What level of disparity in police stops is acceptable, and how do we measure it? If an officer or department crosses this threshold, how long are their future stops presumptively invalid? What is to prevent them from simply tweaking their numbers, potentially by increasing the overall number of pretextual stops (albeit this time of nonminority motorists)?

I’m not suggesting that there are no answers to these questions so much as highlighting just how incredibly difficult they are to answer. Justice Scalia acknowledged the futility of trying to solve this problem in the typical criminal proceeding: “For the run-of-the-mine case, which this surely is, we think there is no realistic alternative to the traditional common-law rule that probable cause justifies a search and seizure.”

The judicial restraint in Whren can be frustrating when viewed as a missed opportunity to strike a blow against pretextual policing. Such a narrow perspective, however, misses the second- and third-order consequences of an opposite holding that could have wreaked havoc as they reverberated through criminal jurisprudence. While we can all lament the perpetuation of pretextual policing, we should probably be thankful that the Court left the problem for more appropriate bodies to solve.