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The Force Science Institute (FSI) referenced a scientific study published in the journal, “Medicine, Science, and the Law,” examining arrest-related deaths attributed to “compression asphyxia” and associated with a subject’s inability to breathe from law enforcement officers “kneeling, sitting, or lying on a resistant suspect’s upper body to establish and maintain control for handcuffing.”

Though unable to identify a medical cause, a similar line of thinking has been historically used in addressing arrest-related deaths involving positional asphyxia, vascular neck restraint, CEW use (Tasers), and Oleoresin Capsicum aerosols (pepper spray).

Research leader, Dr. Mark Kroll suggested "it was 'crazy' to consider it a realistic possibility in the context of police street practices. "Weight on the chest as a cause of arrest-related death?” Dr. Kroll continued, “No way!”

Dr. Kroll cited foundational experiments at the University of California-San Diego that “showed that a prone, hog-tied subject could withstand 225 pounds of weight on his back and still breathe just fine.” Dr. Kroll continued, “The pressing data shows that about 400 pounds on the chest was survivable because of diaphragmatic breathing, with communication still possible, but over 626 pounds was fatal.” Dr. Kroll and his colleagues sought to objectively identify the specific amount of traumatic force necessary to kill someone via compression asphyxia (associated with broken ribs/“flail chest”).

The study found that approximately 570 lbs. of pressure on the front or back of the torso of a male subject in his 20's or 30's is required to break six ribs sufficiently to cause a fatal flail chest. Dr. Kroll reported, “In other words, it would take two 285-pound cops standing and balancing on the back or chest of a suspect to produce compression asphyxia. And that’s simply not going to happen in the real world. Even if an officer were to drop forcefully on his knees onto a suspect, “it wouldn’t significantly change things. The weight of dynamic force from dropping needed to cause death is actually higher than the amount of necessary static weight piled on a subject, because the rib cage has an impressive built-in ability to absorb the physical shock of sudden impact.” Dr. Kroll suggests the findings "are relevant for most subjects who resist arrest and might end up in a compression situation."

Dr. Kroll opined to the FSI, “Sometimes when people fight the police the human body seems just to run out of gas for reasons that aren’t understood. These aren’t murders, yet the explanation is not clear and it’s not right to tie them to junk causations with no basis in science. I believe we need a new cause-of-death category: Arrest-Related Death Syndrome. We can name it first and understand it later as we learn more about it.”


Should the results of scientific studies be regarded in the objective analysis of a law enforcement use of force? Why, or why not?

How should a law enforcement use of force be discussed if public perception and opinion conflicts with scientific data?

If someone disagrees with current scientific data, what is required to support their disagreement? When, or should, the requirement to support a disagreement with existing data be waived?


Kroll, M., Still,G.K., Neuman, T., Graham, M., Griffin, L. (2017) “Acute forces required for fatal compression asphyxia: A biomechanical model and historical comparisons.” Medicine, Science and the Law. First published date: April 3, 2017 (10.1177/0025802417695711).

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