Introduction
Two days before Christmas in 2020, the Quinto family of Antioch, California, was in a desperate situation. Angelo Quinto, a thirty-year-old Navy veteran, was suffering from a mental health crisis.1 Earlier that year, Quinto had been assaulted and experienced a traumatic brain injury, which led him to have episodes of paranoia — one of which seemed to be occurring that December evening.2 Quinto began acting aggressively, and the family called 911 for help.3 When police arrived, Quinto’s family said that his mother was holding him in her arms and that he was calm.4 Officers Perkinson and Becerra grabbed Quinto from his mother and pinned him face down on the ground.5 While Quinto “pleaded ‘please, don’t kill me,’” the officers put Quinto in a prone restraint.6 His hands were handcuffed behind his back and his legs were crossed and bent backward.7 According to the Quintos, officers then held Quinto down by keeping a knee pressed behind his neck over a period of five minutes8 — a situation not unlike what happened to George Floyd in Minneapolis, Minnesota, earlier that year.9 Quinto became unresponsive.10 When the officers “flipped [him] over, . . . blood [had] pooled [under]neath his face.”11 Quinto was taken by ambulance to Sutter Delta Medical Center, where he later died.12
Shortly after the death, the local coroner’s office performed an autopsy, and determined that Angelo Quinto died because of “Excited Delirium Syndrome due to Acute Drug intoxication” — referencing a diagnosis that the District Attorney described as a “physiologic response seen in arrest related death[] . . . scenarios, in which the decedents experienc[e] drug intoxication, exhaustion, [or] pre-existing physical or psychiatric conditions, all of which may trigger fatal cardiac arrhythmias.”13 Put differently, the coroner’s office concluded that Angelo Quinto died due to psychosomatic problems that led him to become so physically agitated, he simply died on his own with no one else to blame.
This finding shocked the Quinto family, who had watched Quinto’s brutal treatment by the police. Confused by the idea that only Quinto was responsible for his death, the family had a second autopsy performed by Dr. Bennet Omalu.14 Omalu found that Quinto’s eyes showed evidence of petechial hemorrhages15 — signs of asphyxiation where strangulation leads blood capillaries in the eyes to burst.16 While being deposed, Dr. Ikechi Ogan, the first pathologist who made the excited delirium diagnosis, “was shown a photo of Quinto’s eyes.”17 Ogan agreed, on the record, that the unusual hemorrhages in Quinto’s eyes were clearly visible.18 Yet the autopsy report failed to mention “key signs” of Quinto’s asphyxiation.19
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Twenty-three-year-old Elijah McClain left a convenience store in Aurora, Colorado, one summer evening in 2019.20 As the small-framed Black man walked down the street, “someone called 911” because they believed that McClain “looked sketchy” since he “was wearing a ski mask” and appeared to be acting erratically.21 When McClain was confronted by three officers, he tried to explain that he did not mean to cause any trouble.22 He pled with them, saying, “I am an introvert . . . . Please respect my boundaries,” “I’m just different,” and “I don’t even kill flies” to prove that he was not dangerous.23 Nevertheless, the officers proceeded to restrain McClain, placing him in a chokehold and putting him in handcuffs.24 During this struggle, McClain told the officers he was having difficulty breathing and then vomited and apologized to the officers.25
Paramedics arrived and determined in that moment that McClain’s visible agitation was a sign that he was suffering from “excited delirium.”26 The paramedics injected him with ketamine — a potent drug with a sedative effect that is increasingly given to people thought to exhibit this condition.27 This approach to “treating” excited delirium is not uncommon, and using chemical restraints is thought by some to be a less harmful alternative to physical force.28 But “body camera footage shows that [the dose of ketamine] made [McClain’s] body go limp when he was loaded onto a gurney.”29 While being transported to the hospital in an ambulance, McClain experienced cardiac arrest and passed away shortly afterwards.30
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Waters v. Coleman,31 a 2015 decision from the Tenth Circuit Court of Appeals, concerned the death of Alonzo Ashley, who was killed during a struggle with police at the Denver Zoo.32 After being confronted by police for allegedly attacking a security officer, Ashley began walking toward the zoo exit.33 Another officer noticed that Ashley was sweating heavily, which the federal judges on the Tenth Circuit described in their opinion as “a symptom of a physiological condition known as excited delirium,” that “often [makes it] impossible to control [these] individuals . . . using traditional pain compliance techniques.”34 Ashley stopped and moved toward the officers, who then tried to put Ashley’s arms behind his back.35 Punches were exchanged.36 The officers then used tasers multiple times and physically restrained Ashley.37 Ashley was taken “to the hospital, where he was pronounced dead.”38
Ashley’s family brought a federal civil rights lawsuit against the officers for violating his constitutional right to be free from excessive force.39 However, the Tenth Circuit held that the officers were entitled to qualified immunity for the acts they took to restrain Ashley.40 This decision meant the officers could not be sued for these acts, since existing laws did not prevent officers from using such force against someone who was suffering from excited delirium.41 The court concluded that “it would not have been clear to a reasonable officer that the conduct at issue might be unlawful in these circumstances.”42
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Police use of force and accountability have been important topics over the past few years as the public grapples with what many have described as a “racial reckoning”43 following several deaths of unarmed Black people in police custody that were filmed by bystanders and distributed on social and legacy media.44 Much of the conversation in the law literature has focused on exploring doctrinal questions such as how the Fourth Amendment structures conversations about the reasonableness of police force, which can inform whether an officer might be held civilly or criminally responsible.45 Yet, there has been little discussion about how doctrinal assessments regarding reasonableness can be complicated by medical diagnoses that are used to suggest that decedents died from preexisting conditions rather than the use of force. One such diagnosis is excited delirium, which is often used to suggest that some deaths in police custody result not from the force that was used, but from self-induced agitation and physical stress stemming from a psychiatric condition that can lead some people to die spontaneously, through no one’s fault but their own. The vignettes at the outset of this Article highlight several instances where excited delirium has been invoked to explain the deaths of people in police custody, and how this “disease” has been positioned to deflect attention away from questions about the reasonableness of the force used and toward evaluating the decedents’ mental health. For example, as described above with respect to the Tenth Circuit’s decision in Waters v. Coleman, federal courts have used excited delirium diagnoses to shape their determinations of whether police officers can face civil liability under 42 U.S.C. § 1983.46
Law’s deference to this medical diagnosis is curious, particularly since excited delirium does not seem to be a real health condition. In fact, excited delirium is a deeply contested concept among researchers and clinicians. Professional bodies such as the American Psychiatric Association47 and the American Medical Association48 have made public statements on how excited delirium is not an appropriate term or diagnosis. Similarly, two of the main medical guidebooks on identifying and diagnosing psychiatric disorders — the Diagnostic and Statistical Manual of Mental Disorders (“DSM-5”) and the International Classification of Diseases (“ICD-11”) — do not recognize the term as a legitimate disorder or medical condition.49 This professional distancing from the concept reflects a finding easily observable in peer-reviewed scientific and clinical literature: There is little scientific evidence to support excited delirium as a legitimate medical claim and virtually no research that identifies a clear pathology on how this psychiatric condition, even if real, could cause death.50
This tension between law’s regular acceptance of excited delirium and medicine’s deep skepticism gives rise to a question explored in this Article: How has law come to a seemingly settled understanding of a disease that science and medicine largely view as demonstrably unsettled, if not wholly unsupported? To be sure, there are many instances where medical or scientific evidence becomes part of legal disputes in which judges and juries assess the weight and importance of the evidence in relation to the facts of the case.51 But the issue of excited delirium stands apart from other discussions concerning the role of science in legal decisionmaking. Questions regarding excited delirium are distinct from those pertaining to the admissibility of other types of scientific or medical testimony such as DNA evidence. This distinction exists because there are no established standards for determining excited delirium, nor are there any minimal agreed-upon principles shared among professionals. From the perspective of the long history of forensic sciences and expert witness testimony,52 the evidentiary support for excited delirium is much closer to that of the highly questioned (and often discredited) “first generation”53 of forensics (such as bite mark analysis and fingerprinting54) than the more “robust . . . second generation,”55 such as DNA typing.56 Given excited delirium’s methodological and evidentiary proximity to a collection of first-generation forensic practices that many frown upon, how is it that federal courts continue to allow — if not fully support — the use of excited delirium in cases concerning police use of force?
This Article explores these critical questions at the intersection of law and medicine. Part I provides a brief primer on excited delirium, its history and usage in police use of force cases, and arguments that law enforcement and some researchers have made for it as a valid explanation for some deaths in police custody. Part II then takes a closer look at the rules and doctrines concerning expert witness testimony and the admission of scientific evidence into federal courts as a way to situate the broader question that is taken up in Part III: How does excited delirium, a fringe idea within medicine with a deeply questionable origin story, enter legal discussions on police use of force and become a seemingly legitimate medical diagnosis to explain deaths in police custody? To do this, Part III looks at how expert witnesses use excited delirium in federal courts by engaging in an empirical examination that evaluates legal shifts in how this purported medical condition is discussed in the context of claims concerning police use of force, from its first articulation in federal case law in 1998 until 2023. This qualitative assessment unearths early conversations concerning excited delirium in evidentiary proceedings to show how, over time, the rules of evidence came to allow testimony not generally accepted within medicine to morph into legal claims that shape federal courts’ evaluations of use of force cases. By treating its gatekeeping function in relation to expert witness testimony as a procedural inquiry — that is, as a process or series of boxes to check — instead of embarking on a deep assessment of the evidence and its broader implications, law has come to give excited delirium much more credibility than science or medicine ever has.
Through a detailed case-by-case examination of early disputes where excited delirium was first brought in front of federal courts, this Article shows how we have landed at a rather awkward moment when legal decisions and subsequent reliance on them as precedent are seen as more relevant to questions about the legitimacy of this medical diagnosis than the scientific research itself — at least in courtrooms where police have been accused of using excessive force. This phenomenon has tremendous implications for how we think about doctrinal rules surrounding expert witnesses, as well as basic notions of justice and accountability, in relation to both civil and criminal adjudications concerning police use of force. Part IV proposes three policy recommendations for how, considering the discussion in Part III, law should respond to both the particular issue of excited delirium in the courtroom and expert witness testimony more broadly — especially as scientific and medical evidence continue to shape legal debates and outcomes regarding police use of force.