Jurors couldn't believe that a reasonable officer would have done what Chauvin did

The prosecution's medical witnesses, including Hennepin County Chief Medical Examiner Andrew Baker, all agreed that the use of force caused Floyd's death. Chicago pulmonologist Martin Tobin explained in detail how being pressed against the pavement by Chauvin's knees and the other officers' hands would have made it impossible for Floyd to breathe properly. Tobin was highly credible and unflappable, and his testimony reinforced the commonsensical inference that a man who complains 27 times that he can't breathe while being squeezed between three cops and the asphalt might actually be having trouble breathing. Other expert witnesses explained why neither heart disease nor drug use were plausible explanations for Floyd's death. And although Baker did not mention asphyxia in his autopsy report, on the stand he did not rule out the possibility that impeded breathing contributed to Floyd's "cardiopulmonary arrest," saying, "I would defer to a pulmonologist." To prove causation, the prosecution needed only to persuade the jury that Chauvin's actions were "a substantial causal factor" in Floyd's death. "The fact that other causes may have contributed to George Floyd's death does not relieve the defendant of any criminal liability," Schleicher noted. "He's criminally liable for all of the consequences of his actions that naturally occur, including those consequences brought about by intervening causes." The alternative to concluding that Chauvin killed Floyd was to believe that Floyd just happened to die from other, unrelated causes under Chauvin's knee.