Police have long known the dangers of holding people in prone restraint. So why do so many keep dying?

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As far back as the 1990s, medical experts and law enforcement officials have been aware of the dangers of prone restraint. A number of organizations and law enforcement agencies, including the US Department of Justice, the Chicago police department and the New Orleans police department, warned officers of these dangers and advised them on how to minimize risks.

Many training manuals have since been updated to address the risks of prone restraint and the importance of using the recovery position. Ohio state police officers are forbidden from using prone restraint. A Nevada law forbids the practice. In California, a law that became effective in 2022, AB 490, bans any maneuvers that put people at risk of being unable to breathe due to the position of their body, or positional asphyxia, a common cause of death in prone restraint cases.

But a new review of law enforcement data shows that, despite growing awareness of the dangers of prone restraint, in California the problem is pervasive. After the passage of AB 71, in 2015, California began tracking data about when people died after police use of force. Between 2016 and 2022, at least 22 people have died in the state after being restrained stomach-down by law enforcement officers, according to a new analysis of currently available state use-of-force data by the California Reporting Project, the California Newsroom and the Guardian. Our examination also included police reports, death investigations, district attorney reviews, body-worn camera footage, 911 calls and lawsuits.