Should Judges Defer to Police Expertise?

At the 2006 trial of a defendant charged with selling marijuana to an undercover agent—charges procured, the defense protested, through unlawful police entrapment—an attorney invited the arresting officer to share his extensive background in narcotics investigation. Detective Felix Aguirre, the attorney reminded the jury, was “an experienced undercover cop” who specialized in hand-to-hand sales as his area of “expertise,” having participated in some 600 to 700 arrests. The officer, he emphasized in closing arguments, is “very good at what he does.”

That anecdote should sound familiar. It fits a common pattern of prosecutors extolling the expertise of law enforcement agents in a bid to impress judges and jurors, boosting the credibility of police witnesses and strengthening their cases in court. At this trial, though, there was a twist. The lawyer pressing Detective Aguirre on his investigative “expertise” wasn’t the prosecutor. He was the defense attorney. 

Over the past decade, lawyers and scholars have commonly taken aim at judicial deference to police expertise: the notion that trained, experienced officers bear unique skills and insights in the field. Such rhetoric abounds in legal disputes about police misconduct, diffusing challenges to unlawful evidence, defraying concerns about unreliable identifications, deflecting allegations of excessive force, even appeasing criticism of vague criminal statutes. Its persuasive appeal is such that prosecutors often invoke expertise even when it has no real bearing on the legal standard—offering it as a type of atmospheric claim to deference, endowing officers with a broad halo of legitimacy. 

Critics have questioned the merits of this practice, not least the controversial claim that police officers are experts to begin with. But the underlying link between expertise and deference remains unquestioned. That connection seems obvious, emblematic of people’s intuitions about relative competency and judicial decision-making well beyond the criminal law. 

In fact, in a variety of legal debates about police misconduct, that dynamic gets flipped on its head. In disputes ranging from coerced confessions to entrapment to excessive force, the rhetoric and hallmarks of expertise—courses of training, years of experience, claims of professional skill and insight—do not boost the presumptive legality or legitimacy of police conduct. Rather, they undermine it, bolstering challengers’ criticisms of police abuse and driving adverse judgments against the state. The claim in such cases—as with the defense attorney’s winks at Aguirre’s “very good” performance—is not that more expert police officers may use their skills to deliberately flout judicial restraints, becoming experts, in effect, at the work of evading the law. It is that the same talents typically touted as markers of “good” policing, reflecting police departments’ own positive accounts of their professional training and skill-building, actually heighten legal concerns.

In a recent article in the Yale Law Journal, I walk through three examples of such adversarial appeals to police expertise at some length–but I’ll briefly summarize them here. First, there’s the case of coerced confessions. As in more familiar disputes about policing, prosecutors countering claims of coerced confessions—especially claims of false confessions—sometimes play up officers’ professional training and experience by way of defending their interrogation tactics. Yet expertise also emerges in the opposite posture. Beginning even before the Supreme Court’s 1966 ruling in Miranda v. Arizona, which imposed new procedural limits on police interrogators largely in recognition of their growing sophistication, defendants have emphasized officers’ mastery in the interrogation room, from rarefied psychological insights to skills at earning suspects’ trust, to argue that those officers elicited involuntary statements. Capitalizing on the central concern animating the courts’ Fifth Amendment doctrine—not simply that coercive methods may elicit false confessions, but that even true confessions procured against a suspect’s will violate the law’s respect for personal autonomy—such defendants suggest that more expert interrogators are simply more capable of breaking down a suspect’s defense, overbearing his will in violation of the Constitution. And judges often agree. A court’s willingness to suppress a confession often tracks the voting judges’ view of the relative skillfulness of an interrogator’s methods, with defendant-friendly judges emphasizing the sophistication, subtlety and power of such tactics, while their more skeptical colleagues downplay—or even expressly note the absence of—any professional training or skill.

A similar dynamic arises in disputes about entrapment. Here, too, some prosecutors make familiar appeals to expertise, extolling undercover agents’ field training, unique role-playing skills or records of prior arrests as evidence of their professional authority—often less as directly relevant evidence than as a type of deferential scene-setting. Often, however, defendants harness that same rhetoric to their advantage, emphasizing the agents’ specialized training and skillfulness in the field—including the same talents emphasized by the state—as evidence that those agents enticed them into crime. Exploiting the deeper principles that underlie judicial skepticism of police entrapment—not only sympathy for otherwise “innocent” suspects, but also a deeper distaste for the fundamental unfairness of manipulative police practices—such arguments suggest that officers’ professional skills enabled them to bring more powerful pressures to bear, inducing the offense or overcoming the defendants’ lack of predisposition. Judges who side with defendants often echo such rhetoric, while prosecutors and officers, ironically, find themselves in the unusual position of minimizing officers’ credentials and experience. 

A final example involves claims of excessive force. Recalling a common practice at Fourth Amendment suppression hearings, police officers in such cases often play up their training and experience as evidence of their superior judgment, demanding deference from lesser-informed jurors and judges. Judges often embrace these broad claims, warning against “second-guessing” police officers’ professional decisions. But challengers, including civil plaintiffs and prosecutors at criminal trials, sometimes invoke those same credentials to make the opposite point, arguing that conduct seemingly reasonable to lay jurors was actually unreasonable for law enforcement experts trained to navigate hostile encounters. Some argue that the defendants’ professional credentials should have altered how they perceived the facts—allowing trained, experienced officers, for instance, to recognize the plaintiff’s lack of violent intent, or to maintain composure in turbulent scenes. Others offer those professional skills as themselves among the facts at play—insisting, say, that even a concededly threatening individual posed no danger to officers trained in self-defense. In both cases, such challengers effectively recast police officers’ expert credentials as grounds to heighten rather than diminish scrutiny, often successfully convincing courts to do the same.

Notably, these three examples make slightly different analytic moves. In the case of excessive force, challengers use claims of police expertise to raise the legal standard to which officers are held, blaming individual officers for not using their expertise in a given encounter. In the case of entrapment and coerced confessions, by contrast, it is the use of expertise itself that drives legal concerns—suggesting, in effect, that more expert officers are likelier to veer past the bounds of permissible conduct. All three examples, however, challenge the conventional account of police expertise in a similar way: They exemplify how looking beyond any presumptive link between expertise and judicial deference, to consider the precise nature of an officer’s expertise and its interaction with a legal claim, may fuel rather than assuage legal concerns.

These divergent courtroom strategies, I argue, are not simply a matter of creative lawyering or clever rhetoric. Rather, their persuasive power reflects a tension between two fundamentally distinct conceptions of police expertise—and, by extension, of expertise more generally—that pervade judicial reasoning: what I term the difference between seeing expertise as a professional virtue or a professional technology. 

Echoing popular accounts of expertise as a prized currency in a technocratic culture, the virtuous model imagines expertise as a presumptive institutional good. By this view, the achievement of “expert” status, endowing agents with superior knowledge, experience, and skill in their field, commands an inherent measure of authority, to be recognized and respected by other institutional actors. My article traces a number of ways of making this leap, from sociological presumptions about the disciplining effects of expert credentialing to technocratic celebrations of expert status as a hard-won accomplishment worth rewarding in itself. Regardless, this model assumes that expertise, once established to a court’s satisfaction, justifies a default posture of deference, without much additional inquiry into its operations in a given case. It is this view that undergirds prosecutors’ often-impressionistic—and surprisingly successful—appeals to expertise even when its immediate relevance remains unclear. 

The technological view, by contrast, imagines expertise as a professional capacity: something that does no more—and no less—than facilitate the successful performance of investigative tasks, expanding the police’s power in the field. Severing any direct link between expertise and legality, that is, it sees advances in police expertise as developments that tip the law’s delicate balance between individual rights and state power, straining the boundaries guarded by the courts’ criminal-procedure doctrines in a way that may predictably fuel greater oversight. Which is to say, this model treats expertise as courts have long treated the more familiar technologies of policing, from wiretaps to thermal imaging devices to sophisticated location trackers. In those cases, it is well recognized that technological advances that genuinely improve the police’s ability to detect evidence—making them, in some sense, better at their investigative work—do not necessarily deflect but fuel judicial skepticism. The cases surveyed above treat expertise—advances in the police’s human assets—the same way. 

This is a more institutionally realistic view of expertise. Rather than embracing expertise as a generic good, it examines how specific advances to police proficiency shift the operations of policing in each case. And rather than presuming a consistent relationship between expertise and legality, it examines how police expertise interacts with the precise goals served by judicial review, acknowledging that the courts’ criminal-procedure doctrines defend a variety of justice values that may react very differently to the introduction of more “expert” policing. In the case of doctrines centered on accuracy, such as the Fourth Amendment’s standards of criminal suspicion, greater training and experience might logically be thought (theoretically, at least) to boost the precision of officers’ judgments, exposing them to more specialized information. But in the case of doctrines centered on autonomy, on fundamental fairness, or on preventing abuse of state power, the promise of a more proficient police force—one staffed by officers better capable of reassuring cautious suspects, or of creating irresistible temptations, or of navigating hostile scenes—plays very differently. A technological approach to police expertise recognizes that, in a system administered by multiple agents of the law, guided by their own internal goals and pressures, the significance of police expertise cannot be presumed—and certainly not taken as a de facto right to deference. Rather, it rests on the interplay between such expertise and the values animating a legal challenge: what it is that officers are expert at and how that intersects with the objectives of judicial review. 

What might be gained from recognizing these rival views of expertise?

First, parties challenging police misconduct in court can derive useful strategic insights. Taking a technological approach of expertise—by far, I argue, the more defensible view—offers new tools in a variety of criminal-procedure cases. That includes, most basically, proliferating the types of challenges surveyed above. Despite the often-surprising success of police expertise in boosting claims of coerced confessions, entrapment and excessive force, challengers in these fields still often take a more traditional approach, ceding expertise as a natural boon to police authority and trying their best to expose the limits of such skill. Recognizing how even conceded claims of police expertise may actually support their arguments—illuminating troubling power imbalances, fanning qualms about immoral tactics, or simply demanding that officers live up to their professional talents—provides a powerful new line of attack. 

That strategy also reaches beyond the cases above, enriching legal disputes that involve substantially similar dynamics. Debates over a defendant’s voluntary consent to a police search, for instance, often come down to concerns about police intimidation or power imbalances nearly identical to those at issue in disputes about coerced confessions. Debates about the existence of probable cause, too, lend themselves to adversarial uses of expertise analogous to those in litigation over excessive force—a context where, thus far, they have been far more common. 

Perhaps most tantalizingly, a technological approach might shift judges’ understandings of when police conduct raises constitutional concerns to begin with. Take, again, the Fourth Amendment’s bar on reasonable searches or seizures. Approaching police expertise as a tool that expands police power, no different from any other police technology, suggests that officers’ reliance on their expertise to gather grounds for an arrest—say, identifying narcotics in a suspect’s pocket on the basis of “plain touch”—does not simply help establish probable cause, assuaging Fourth Amendment concerns. It may qualify as its own “search” of Fourth Amendment significance. Recognizing officers’ rarefied sense of plain-touch as a surveillance instrument in itself—an investigative tool used to reveal private data otherwise shielded from public view—may result in additional procedural restrictions on the types of frisks and pat-downs that currently proliferate in encounters between police officers and (typically male, typically Black) members of the public, reducing an overused and profoundly invasive regime of street patrol.

Certainly, a technological approach to expertise will not eliminate judicial deference to law enforcement. But it will hold police officers and prosecutors to their proof, demanding that those who seek to benefit from police expertise explain how such credentials advance the goals of judicial review. In a criminal justice system staffed by an increasingly professionalized police force, bearing so many hallmarks traditionally associated with institutional competency, a technological approach will pry expertise from the hands of the police, revealing how that development raises new issues for—and imposes novel obligations on—judges committed to the protection of individual rights.

At the same time, the courts’ dual encounters with police expertise illuminate debates about deference and professional competency beyond the criminal law. 

For one thing, the courts’ competing paradigms expose the extent to which our associations between expertise and deference rest on an essentially virtue-based view of expertise—one at odds with prevailing defenses of deference to begin with. From legal philosophers to scholars of the administrative state, commentators have long distinguished between epistemic and authority-based theories of judicial deference: the former reflecting an agent’s superior ability to ensure good legal outcomes, while the latter rests simply on the agent’s institutional status or identity. Given a choice, commentators nearly universally embrace the first as more legitimate, alone consistent with the courts’ duties to vindicate the demands of the law. 

Judicial encounters with law enforcement—and, specifically, the persistence of the virtuous view—reveal the instability of that distinction. Those encounters demonstrate how easily, in a legal culture that valorizes technocratic achievement, claims of expertise may take on a legitimating halo that supports its own essentially status-based bid for deference, grounded less on any deep engagement with the advantages of expert policing than on officers’ mere claims to be professional experts. The example of police expertise reveals how the hallmarks of expert status and credentialing, just like more traditional stories about political accountability or constitutional structure, can provide a foundation for identity-based deference. And it exemplifies the dangers of this slippage, showcasing how under-interrogated expert claims may ossify into demands for authority without any real claim to refining legal outcomes. Well past the criminal law, in disputes ranging from prisoners’ rights to university matters to disability-related challenges, critics have protested the tendency of expert claims to exact uncritical deference from judges—often despite the meager nexus between those claims and the legal questions at issue. The virtuous model offers a novel lens on these disputes, attributing such self-abnegation not to judges’ misunderstandings of the legal frameworks or the institutional incentives, but to the hagiographic draw of expertise itself, which may distract observers from thinking more critically about such arguments.

At the same time, judicial encounters with police expertise sever the link between expertise and deference itself: the presumption that expertise is a trump card in disputes about comparative authority, or at least an institutional advantage. If the virtuous model exposes the legitimating power of expertise when viewed too uncritically, the technological model reveals expertise as something that can undermine institutional legitimacy—something that may, in fact, be a liability. 

Historians and sociologists of knowledge have long examined the contingent process through which professional groups aspire to the status of “expert,” a process shaped by countless social, cultural and institutional considerations beyond technical mastery. Most, however, still cast successful claims to expertise as reliable sources of capital. Critics who do question experts’ entitlement to deference tend to situate their critiques within broader political attacks on expertise writ large, decrying its subjectivity or inherent elitism.

The treacherous legal status of expert policing suggests an additional wrinkle: the extent to which an audience can fully concede an assertion of expertise but nevertheless take that concession, not as a claim to authority, nor even as a net-neutral, but as a source of active mistrust, scrutiny and resistance. And it may do so not simply because of the substantive limits of expertise or due to any ideological skepticism of expertise per se, but due to the thorny implications of what it means to be an “expert” at certain inherently controversial professional tasks. The unique skepticism inspired by expert officers using their prodigious skills to ease individuals toward criminal temptations or gain the trust of vulnerable suspects exemplifies the ambiguous significance of expertise in a realm of public service that is both broadly accepted as common—indeed, often celebrated as important—and nevertheless lends itself to lingering ethical concerns. In that, it also compels society to reexamine its commitment to certain government functions—like so many apparently entrusted to the police—that the law has decided it wants its agents to perform only if they do not become too good at them.