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 stopsmay 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.