Since 2000, more than one thousand people in the U.S. have died shortly after being stunned with a Taser by police officers.  These deaths share several commonalities: the deceased often were mentally ill or under the influence of drugs at the time of death, they tend to have been shocked multiple times by officers during arrest, and they often share an exceptionally rare cause of death, “excited delirium.” Proponents of the excited delirium diagnosis say it refers to spontaneous deaths caused by extreme agitation often catalyzed by drug use—essentially death by an excess of adrenaline and stress. Skeptics call it an unscientific fabrication used to cover up police killings, as evidenced by the strong correlation between police violence and deaths attributed to excited delirium. If these really are spontaneous deaths, these skeptics wonder, why are so many of them occurring only after altercations with police?

The origins of excited delirium

In 1985, two University of Miami professors, Charles Wetli and David Fishbain, set out to explain what they saw as a puzzling new phenomenon: sudden deaths, mostly in police custody, of otherwise healthy men under the influence of a non-lethal amount of cocaine. “Excited delirium” was the term they coined to describe the state of agitation in which these individuals allegedly ignored pain, lost touch with reality, and spontaneously died. This newly theorized cause of death never caught on in broader medical circles, and has not been approved by the American Medical Association, the American Psychiatric Association, the World Health Organization, or been featured in the Diagnostic and Statistical Manual of Mental Disorders.  Recognition of the existence of agitated states is universal, but the claim that one can kill a person has proved to be far more niche.

Excited delirium as a cause of death has also struggled to find mainstream support given its history of bad press. Shortly after publishing his first article on the topic, Dr. Wetli publicly attributed a string of women found dead in various states of undress in Miami to a form of excited delirium in which the women died spontaneously during sex. Dr. Wetli told reporters that this was a new variation of the phenomenon he said was killing men after encounters with police, saying “the male of the species becomes psychotic and the female of the species dies in relation to sex” during an excited delirium. Police later announced that they had arrested a serial killer they believed was responsible for the deaths.

More recently, the concept of excited delirium has drawn fire as media outlets have highlighted how Taser International, now Axon, pushed the theory on medical examiners. The company , these reports explain, has paid thousands to Dr. Wetli and other proponents of the excited delirium diagnosis to testify on its behalf in court. It proactively seeks out medical examiners charged with identifying a cause of death in Taser-involved deaths, sometimes mere hours afterward, lobbying them in favor of a finding of excited delirium. In one case, the company told medical examiners to contact a researcher who had published favorably on excited delirium without disclosing that they had previously paid her around $24,000 in expert witness fees; in another, the company sent representatives to a deputy coroner’s office immediately after he had attributed a man’s death to Taser shocks. The company also broadly distributes books and information defending excited delirium to medical examiners and police and has offered a pre-written statement about excited delirium for police departments to release following Taser-related deaths.

Excited delirium and the law

Axon and the police departments that use its products have repeatedly used the excited delirium theory in court as a shield against liability—Axon has touted its ability to get suits against it dismissed along these lines. Individual officers have also enjoyed protection from criminal prosecution under the theory. When medical examiners attribute deaths to excited delirium instead of linking them more directly to police violence, it becomes an uphill battle for plaintiffs to prove causation by police or Axon.

Perhaps understanding the importance of this protection, Axon has actively pursued litigation against some medical examiners who attribute deaths to Tasers rather than excited delirium. These lawsuits seem to have a chilling effect on medical examiners’ work; a 2011 survey found that 14% of medical examiners had modified a diagnostic finding out of fear of litigation by the company.

To skeptics, this state of affairs paints a disturbing picture: a company that has popularized a dubious medical diagnosis for the purpose of avoiding liability for its product. Undoing this campaign would undoubtedly be difficult, but signs of hope exist. For one, the increasing media attention on this issue adds countervailing voices against Axon’s pro-excited delirium messaging. The courts are also showing some signs of doubt as to the legitimacy of excited delirium; by one count, 63% of wrongful death cases against police departments that cited Tasers as a contributing factor ended either in settlement or a judgment for the plaintiffs. But before this trend can spread to suits directly against Axon, or broadly empower suits where Taser abuse was the sole factor allegedly leading to a death, groups must begin confronting the theory of excited delirium head on.