More than half of police killings in the United States over the past 40 years have been mislabeled, according to a new study, leading to a stark undercount of deaths at the hands of officers and a lopsided perception of what experts say is a public health crisis.

Researchers from the University of Washington found that from 1980 to 2019, more than 55 percent of 31,000 deaths attributed to police violence were assigned other causes in official federal death data. Black men are killed by police at disproportionately high rates, and their deaths are mislabeled at higher rates than for any other race, according to the study, which was published Thursday in the Lancet, a peer-reviewed medical journal.

The study underscores a grim reality: Despite years of scrutiny, criticism, protests and calls for reform, no government agency tracks how often law enforcement officers in America kill people. Since 2015, The Washington Post has been counting how often on-duty police shoot and kill people. But there is no comprehensive federal attempt to keep track of these deaths or other uses of force by law enforcement, including chokeholds and nonfatal shootings. One of the study’s authors called the deaths poorly catalogued and preventable, and an expert said the lack of meaningful tracking of these deaths underscores the deep-rootedness of systemic racism.

High-profile police killings over the past several years, such as that of George Floyd in May 2020, have led to nationwide calls for police reform and an examination of why Black men are disproportionately killed during police encounters. But until now, this study’s authors say, the true scope of police killings has been largely unknown.

Police and a medical examiner initially attributed Floyd’s death to drug use and underlying conditions, despite bystander video showing former police officer Derek Chauvin kneeling on Floyd’s neck and back for more than nine minutes. Chauvin was found guilty of murder and manslaughter in April.

The study compared decades of data from the National Vital Statistics System, which tracks births and deaths, to three databases that track police violence: Fatal Encounters, Mapping Police Violence and the Guardian’s The Counted. The databases sift through news reports and public records for instances of people killed during police encounters.

Mohsen Naghavi, the study’s senior author, told The Post that it is critical to look beyond the incomplete data provided by government agencies.

“Here the role of the media is very important,” he said. “If we didn’t have the media, we wouldn’t have open-source data.”

Noting the striking discrepancy between the study’s findings and the government’s data, the authors called for public health officials and researchers to “swiftly adopt open-source data-collection initiatives to provide accurate estimates and advocate for policy change to address this long-neglected public health crisis.”

Researchers identified places where misclassification of deaths often occurred, noting that medical examiners or coroners — who must fill out the cause of death when there is suspicion of foul play, including police violence — can be embedded in or work for police departments.

If the medical examiner, coroner or other certifier fails to indicate police involvement in the cause of death on the death certificate, the incident could be misclassified.

The study underscores how deeply enmeshed systemic racism is in different aspects of life — including health, said Edwin G. Lindo, assistant dean for social and health justice at the University of Washington School of Medicine.

“We have to really sit back and say, ‘What does this mean?’” the critical race theory scholar told The Post. “In my mind there is a deep-seated undercurrent of systemic racism to the point that a medical examiner doesn’t have to declare that they’re racist. The practices are already showing, and the racism is occurring, not just during the encounter itself, but even after the individual has passed away.

“There’s still acts of racism trying to hide the murder or the killing that occurred,” he said.

The study’s authors said forensic pathologists should be independent from law enforcement to avoid incorrectly identifying the cause of death due to outside pressures. They also said the experts should be offered whistleblower protections so they can fully investigate police violence.

“We need the government and policymakers to fix this conflict of interest because violence is a public health crisis,” Naghavi said.

Researchers found Black people were 3½ times more likely than White people to be killed by police, and Latinos and Native Americans also faced higher rates of fatal violence at the hands of law enforcement. About one in every thousand Black men in the United States is killed by police, the study found.

“Systemic and direct racism, manifested in laws and policies as well as personal implicit biases, result in Black, Indigenous, and Hispanic Americans being the targets of police violence,” it read.

Lindo said the number of people dying at the hands of police highlights how this violence is a major public health problem.

“That is a mortality rate greater than the likelihood of you dying of riding your bicycle in the United States, and riding your bicycle is dangerous,” he said.

Underreporting also most dramatically affected Black people, the study found, with nearly 60 percent of deaths misclassified. Men were more than 20 times more likely to be killed than women. In 2019, the study said, more than twice as many men died from police encounters than from testicular cancer.

“This is important because it kills more than some important disease, and it is preventable,” Naghavi said.

Misclassification rates varied broadly from state to state, with researchers finding Oklahoma incorrectly labeled more than 83 percent of deaths by police, Wyoming more than 79 percent, and Alabama, Louisiana and Nebraska all over 72 percent. Maryland had the fewest estimated misclassified police killings at around 16 percent.

Oklahoma, Arizona, Alaska and the District of Columbia had the highest rates of police killings, according to the study.

After police in Ferguson, Mo., killed Michael Brown in 2014, a Post investigation found that the FBI undercounted fatal police shootings by more than half. Most U.S. police departments have declined to share data with the National Use-of-Force Data Collection since its launch in 2019 — despite a presidential order and other pressure.

Lindo said the underreporting is “an act of dehumanizing the death of these communities.”

Obscuring the actual figures of deaths from police violence compounds mistrust in the government and could also lead to greater impunity for officers, Lindo said.

With such discrepancies in how police deaths are reported, Lindo said the study is primed to generate attention. Yet, more than a rude awakening, the professor said, the findings should catalyze action.

“What the study doesn’t speak to and what we need to focus on … is that the underreporting doesn’t necessarily mean that the behavior of the police brutality changes immediately,” he said. “And so while, yes, we focus on how severe this underreporting is, we also have to identify the tactics to make sure that this police violence no longer exists.”

Mark Berman contributed to this article.

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