Exactly Where Was Derek Chauvin's Knee, and Does It Matter?

A use-of-force expert says the officers who pinned George Floyd to the ground should have recognized the risk of positional asphyxia.

Los Angeles Police Department Sgt. Jody Stiger, a use-of-force expert who testified for the prosecution in Derek Chauvin's murder trial, agrees with Minneapolis Police Chief Medaria Arradondo that the defendant violated his department's policies when he pinned George Floyd to the pavement with his knee for more than nine minutes. Stiger, who testified yesterday and today, elaborated on the reasoning behind that conclusion.

At the time of Floyd's May 25 arrest for using a counterfeit $20 bill to buy cigarettes, the Minneapolis Police Department's Policy and Procedure Manual said an officer "shall only use the amount of force that is objectively reasonable in light of the facts and circumstances known to that [officer] at the time force is used." Tracking the Supreme Court's guidelines in the 1989 case Graham v. Connor, those facts and circumstances include "the severity of the crime at issue," "whether the suspect poses an immediate threat to the safety of the officers or others," and "whether he is actively resisting arrest or attempting to evade arrest by flight."

In this case, the crime—a nonviolent misdemeanor punishable by a maximum fine of $3,000 and up to a year in jail—was not exactly severe. Stiger agreed with Arradondo that "typically you wouldn't even expect to use any type of force" in "a normal situation where you are dealing with someone…who is using a counterfeit bill."

Eric Nelson, Chauvin's attorney, has criticized Officers Thomas Lane and J. Alexander Kueng for needlessly escalating the situation by trying to force Floyd into the back of their patrol car, which precipitated panicked resistance. Floyd struggled with the officers, saying he was claustrophobic, complaining that he could not breathe, and asking to ride in the front seat. "If Kueng and Lane had chosen to de-escalate instead of struggle, Mr. Floyd may have survived," Nelson said in a pretrial motion.

Stiger agreed with Nelson that a less aggressive approach seemed to be appropriate. "They could have continued to try to verbalize with him," he said. "It appeared early on that Officer Kueng gained a slight rapport with Mr. Floyd….It would have been best to try to continue to verbalize with him, because [Kueng] had gained a rapport with him, and try to get him to comply with his commands by verbalization."

Once Kueng and Lane were struggling to place Floyd in the back of their car, Stiger said, his resistance nevertheless justified the use of force. "Initially," he said, "when Mr. Floyd was being placed in the back of the vehicle, he was actively resisting the officers, so at that point the officers were justified in utilizing force to try to have him comply with their commands and to seat him in the back seat of the vehicle."

After Floyd was pulled out of the car and onto the street, he was initially on his knees, and he thanked the officers for letting him out. At that point, Chauvin, assisted by Lane and Kueng, pinned Floyd facedown on the pavement with his hands cuffed behind his back. As they were tackling him, Stiger said, Floyd moved his leg in a way that could be interpreted as an attempt to kick the officers. But "once he was placed in the prone position on the ground," Stiger said, "he slowly ceased his resistance, and at that point the officers…should have slowed down or stopped their force."

Instead they kept him pinned facedown for nine and a half minutes, even after he was no longer talking or moving and no longer had a detectable pulse. Chauvin, the senior officer on the scene, disregarded Floyd's many complaints that he was having trouble breathing, Lane's repeated suggestion that Floyd should be rolled onto his side, and the objections of bystanders who warned that Floyd's life was in danger.

Since Floyd did not pose "an immediate threat" and was not "actively resisting," Stiger said, the continued prone restraint did not meet the Graham v. Connor test. In addition to the fact that Floyd was not trying to assault the officers or threatening to do so, he said, the presence of five cops at the scene should have factored into their determination of whether Floyd posed any threat that justified their use of force. Based on the video record, Stiger concluded that Floyd "was not actively resisting at the time that he was in the prone position." In these circumstances, he said, "no force should have been used once he was in that position."

Video of the arrest shows Chauvin with his knee on Floyd's neck, a restraint technique that the prosecution says Chauvin used for more than nine minutes. Nelson says Chauvin's knee was actually between Floyd's shoulders "at the base of the neck."

Here is how Stiger described a still from video footage of Floyd's arrest: "That shows the defendant with…his left knee on Mr. Floyd's neck and his right knee on Mr. Floyd's back." Three other stills likewise showed Chauvin's knee on Floyd's neck. Based on his review of the record, Stiger said, those images accurately reflect Chauvin's position throughout the encounter. He said the visual evidence indicates that Chauvin was applying most of his weight to Floyd's body.

The current version of the police department's policy manual, which was revised in response to Floyd's death, prohibits the use of neck restraints. But at the time of Floyd's arrest, police were allowed to use neck restraints in certain circumstances.

The manual defined a neck restraint as "compressing one or both sides of a person's neck with an arm or leg, without applying direct pressure to the trachea or airway (front of the neck)." In one version of the technique, "the subject is placed in a neck restraint with the intention of rendering the person unconscious by applying adequate pressure." That technique, a.k.a. a "sleeper hold," requires applying pressure to both sides of the neck, cutting off blood flow to the brain. Another kind of neck restraint aims to "control" the subject, rather than making him pass out, by "only applying light to moderate pressure."

The first kind of neck restraint was allowed only when the subject "is exhibiting active aggression," when it is necessary "for life saving purposes," or when the subject "is exhibiting active resistance" and "lesser attempts at control have been or would likely be ineffective." The second version—the one that Chauvin seems to have used—was allowed when the subject "is actively resisting."

According to Stiger, however, Chauvin continued to use a neck restraint long after Floyd was no longer resisting. Furthermore, applying most of your weight to an arrestee's neck probably does not qualify as "light to moderate pressure."

Stiger said kneeling on Floyd for as long as Chauvin did amounted to deadly force, because "the pressure that was being caused by the body weight could cause positional asphyxia." He said the danger of positional asphyxia, which has been widely recognized for decades, exists whenever a handcuffed arrestee is restrained on his stomach for an extended period of time. He noted that applying pressure magnifies that risk.

Nelson has said the presence of outraged bystanders distracted Chauvin and the other officers, which he implied helps explain their use of force against Floyd, their failure to render aid when Floyd was no longer responsive, or both. Stiger, who said he has made arrests while surrounded by angry people throwing bottles and making threats, noted that the bystanders in this case were not violent and did not verbally threaten the officers, although they hurled a few insults (such as bum) and used foul language (such as bullshit and fuck). "I did not perceive them as being a threat," he said.

In any event, Stiger said, the behavior of bystanders cannot justify the use of force against an arrestee that would not otherwise be reasonable. He also expressed doubt that the officers were in fact so distracted that they did not realize Floyd was in distress, noting that they heard his complaints and verbally responded to them.

Although the use of force must be "objectively reasonable," Nelson noted while questioning Stiger, that determination is supposed to be based on what "a reasonable officer" would do in the same circumstances. That standard recognizes that "police officers are often forced to make split-second judgments—in circumstances that are tense, uncertain, and rapidly evolving—about the amount of force that is necessary in a particular situation."

Nelson noted that Floyd was already complaining that he could not breathe while Kueng and Lane were trying to force him into their squad car. He suggested that Floyd may have "feigned a physical ailment" to avoid arrest, or at least that the officers perceived it that way and were therefore skeptical when Floyd said he was having trouble breathing—27 times, by the prosecution's count—while pinned to the ground.

Nelson also noted that there was reason to believe Floyd, who had swallowed black-market "Percocet" tablets containing fentanyl and methamphetamine, was under the influence of drugs (although he denied it); that Floyd had resisted so much that the officers were unable to keep him in the car; and that a handcuffed suspect can still pose a threat to police. He argued that Floyd, while restrained on the ground, may have been resisting in a way that was not apparent in the videos—a suggestion that Stiger rejected.

Nelson suggested that Chauvin used a widely accepted prone restraint technique that involves kneeling "between the shoulder blades at the base of the neck," which is "standard practice" across the country. But Stiger noted that "officers are always trained to stay away from the neck as much as possible." Even while implying that Chauvin did not use a neck restraint, Nelson noted that the Minneapolis Police Department at the time authorized the use of that technique against suspects who are "actively resisting."

Regardless of which prone restraint is used, Stiger said, officers have long been trained to "immediately" put arrestees in "a side recovery position" or "sit them up" after handcuffing them, even if they continue to resist. At that point, he said, police can "hold them down in the side recovery position" or "utilize a hobble" that restrains their hands and feet.

Nelson seemed surprised by that information, which is obviously relevant in judging whether Floyd's prolonged prone restraint was reckless, regardless of exactly where Chauvin put his knee or for how long. If prosecutors are not careful, the dispute about the position of Chauvin's knee may obscure the broader question of whether pinning a handcuffed man facedown on the ground for more than nine minutes was objectively reasonable.

When prosecutor Steve Schleicher asked Stiger to clarify whether the risk of positional asphyxia depends on whether pressure is applied specifically to the neck, Stiger said "it's the pressure on the body" that "complicates breathing." Whether Chauvin's knee was on Floyd's neck or, as Nelson prefers to describe it, "between the shoulder blades at the base of the neck," the crucial point is that he was pressing down on Floyd throughout the encounter, which aggravated the asphyxiation risk created by forcing him to lie on his chest with his hands behind his back. That situation made Floyd's complaints that he could not breathe perfectly understandable and plausible, even if the cops thought he was faking.