SCOTT SIMON, HOST:
Another week of testimony in the trial of Derek Chauvin, the former Minneapolis police officer charged with killing George Floyd. This week featured medical experts, who took a closer look at the precise cause of death of Mr. Floyd. NPR's law enforcement correspondent Martin Kaste joins us now to talk about the trial he's been covering. Martin, thanks so much for being with us.
MARTIN KASTE, BYLINE: Sure. Hi, Scott.
SIMON: The first week, of course, introduced the jury to the video that's become seen around the world, and it's so difficult to look at - George Floyd first appearing at Cup Foods all the way down to when he was handcuffed facedown on the street and then under Derek Chauvin's knee for more than nine minutes. How did this week compare?
KASTE: Well, this week is more about the analysis of what happened, first from the point of view of the rules that govern how police may use force, then from the point of view of medical science. The culmination of the week may have been yesterday afternoon, when the Hennepin County medical examiner, Andrew Baker, restated his official finding that Floyd's death was homicide. That is a death caused by another person. And in this case, Baker said Floyd's underlying heart disease contributed to the death, but the cause was the way the police held him down.
(SOUNDBITE OF ARCHIVED RECORDING)
ANDREW BAKER: Those events are going to cause stress hormones to pour out into your body, specifically things like adrenaline. And what that adrenaline is going to do is it's going to ask your heart to beat faster. It's going to ask your body for more oxygen so that you can get through that altercation. And in my opinion, the law enforcement subdual restraint and the neck compression was just more than Mr. Floyd could take.
SIMON: Martin, why was it so vital for the prosecution to have the medical examiner say that?
KASTE: Well, it's because the defense has really been playing up the contributing factors aspect here, talking about Floyd's drug use, his heart disease, trying to show that Chauvin's knee maybe wasn't directly on Floyd's neck the whole time. And the prosecution is saying, yeah, this death is physiologically complicated, but the actions of Chauvin and the other police are what started that chain of events.
You probably know that I cover policing. And what I'm struck by this last week or so is how many people in law enforcement have contacted me saying that they're really watching this trial and really interested in this testimony. Earlier this week, I talked to Joe Giacalone, who's a retired NYPD detective sergeant who now teaches future cops.
JOE GIACALONE: I teach a use of force class at John Jay College. And I think this was going to be a centerpiece of that course going forward.
SIMON: Martin, what do you think many police departments might be learning from this trial?
KASTE: Well, take the issue of positional asphyxia, the idea that someone could asphyxiate just by being facedown with their hands cuffed behind their back. This danger is accepted by a lot of police and trainers, but it's not a universal acceptance. Some trainers resist the idea based on a few laboratory tests that have been done where people have been held in that position and they've seemed to be fine. I remember right after Floyd's death, a police trainer told me he thought positional asphyxia was a myth.
But in this trial, there was a lot of attack by experts on the idea that this is a myth. Listen to forensic pathologist Lindsey Thomas yesterday talking about those lab tests and saying that the young-ish, sort of healthy people in those studies don't have any bearing on the real experience of being cuffed on the street.
(SOUNDBITE OF ARCHIVED RECORDING)
LINDSEY THOMAS: They were being monitored the whole time. And if at any point they had had significant respiratory or cardiac difficulties, the study would've stopped, and the person volunteering knew that. So to me, it just - it bears no resemblance to what Mr. Floyd experienced.
SIMON: Martin, what about the belief that's common among some police officers, and it's come up during the trial, that a person who can talk should also be able to breathe?
KASTE: That's a big one. Several retired cops I've talked to told me that that's what they were taught at least a couple of decades ago. And some police officers may still be learning this idea that if you're speaking, that you can breathe.
But in the trial on Thursday, a top pulmonologist spent a good part of the morning just demolishing that idea, just talking about the physiology of breathing and explaining how someone who's asphyxiating can still muster enough of a shallow breath to say I can't breathe before he dies.
So that's come as a shock to a lot of police who want to do the right thing and relied on that sort of mantra, and now it's being exposed as being quite dangerous. And they're talking about this. I know that. And no matter how this trial ends up, I think that this kind of testimony may have an effect on how a lot of them go about their business.
SIMON: NPR's law enforcement correspondent Martin Kaste, thanks so much.
KASTE: You're welcome. Transcript provided by NPR, Copyright NPR.
