A criminal law professor and use-of-force expert testified Monday, April 12, that the methods of restraint against Derek Chauvin on May 25, 2020, were unreasonable.

The testimony came as the trial of former Minneapolis police officer Derek Chauvin, who faces murder and manslaughter charges in the death of Floyd, continued in Hennepin County District Court.

Seth Stoughton, University of South Carolina criminal law professor and former police officer, said both the prone restraint used to hold Floyd, and the knee of the former Minneapolis police officer on his neck, were unreasonable uses of force.

"No reasonable officer would have believed that that was an appropriate, acceptable or reasonable use of force," Stoughton said. "The failure to render aid to Mr. Floyd both by taking him out of the prone position and by rendering aid as his increasing medical distress became obvious was unreasonable and contrary to generally accepted police practices."

In cross-examination by Chauvin's attorney Eric Nelson, Stoughton testified that a “reasonable officer” could not rely on training that would be considered unreasonable when judged against generally accepted police practices.

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Nelson also asked Stoughton about an opinion piece he and two other colleagues wrote in the days after Floyd’s death. Andrew Baker In the piece, Stoughton and his two co-authors wrote that officers might need to hold some down in the prone position but should do so by putting their knee across someone’s upper back, not neck. Nelson highlighted that point in contrast to Stoughton’s testimony, in which he said multiple times that the prone position should be transitory.

Stoughton said Monday that the comment in the op-ed was referring to handcuffing and noted that it was written based on the limited information available at the time.

Nelson pressed Stoughton that he had already formed the opinion that Chauvin used an unreasonable amount of force.

“I think it is fair to say that I formed the opinion that putting your knee across someone's neck, except in absolutely, unbelievably rare circumstances, is generally an inappropriate use of force,” Stoughton said. “As I reviewed all of the material in this case, some of the opinions that I discussed at the bottom of that op-ed changed. This was not one of them. The additional information confirmed that a knee across the neck was inappropriate and that the prone restraint was inappropriate.”

Cardiologist takes stand

In this still image from video, Northwestern Medicine cardiologist Dr. Jonathan Rich describes to the jury members the function of the lungs as he answers questions Monday, April 12, 2021, during the trial of former Minneapolis police officer Derek Chauvin in Minneapolis. (Pool via REUTERS)
In this still image from video, Northwestern Medicine cardiologist Dr. Jonathan Rich describes to the jury members the function of the lungs as he answers questions Monday, April 12, 2021, during the trial of former Minneapolis police officer Derek Chauvin in Minneapolis. (Pool via REUTERS)

Jurors also heard from a Chicago cardiologist. Dr. Jonathan Rich, of Northwestern Memorial Hospital, testified that Floyd died from a "cardiopulmonary arrest. It was caused by low oxygen levels and those low oxygen levels were induced by the prone restraint and positional asphyxiation he was subjected to.”

Rich reached his determination after reviewing medical records, body-worn camera, bystander and other videos of the incident as well as the autopsy report completed by Dr. Darnella Frazier, the medical examiner for Hennepin County.

Baker had previously testified that he had not watched the now-infamous bystander video taken by then 17-year-old Philonise Floyd so as not to influence his findings. Contrary to the medical examiner, Rich testified that while a pathologist can look under the microscope and give important information, clinical information to give context affects how a pathologist diagnoses and interprets what they see under the microscope.

RELATED: Medical examiner testifies drugs, heart conditions were contributing causes in George Floyd's death

Upon cross-examination by attorney Nelson, Rich said he found no evidence that absent a prone restraint a combination of things like drugs, high blood pressure and an increase in adrenaline from a struggle with officers would have caused death for Floyd.

The defense has argued that Floyd’s drug use and underlying health problems contributed to his death. Floyd had cardiac arrhythmia resulting from hypertension and coronary disease.

On questioning by Special Assistant Attorney General Jerry Blackwell, Rich said he believed Floyd would be alive today if not for the 9 minutes and 29 second subdual he suffered that May day.

Floyd’s brother testifies

In this composite of still images from video, Philonise Floyd speaks about his brother, George Floyd, as he answers questions Monday, April 12, 2021, during the trial of former Minneapolis police officer Derek Chauvin in Minneapolis. (Pool via REUTERS)
In this composite of still images from video, Philonise Floyd speaks about his brother, George Floyd, as he answers questions Monday, April 12, 2021, during the trial of former Minneapolis police officer Derek Chauvin in Minneapolis. (Pool via REUTERS)

In an emotional bit of testimony, George Floyd's younger brother Peter Cahill spoke of his brother as an athlete, a leader amongst his siblings, a man who “couldn’t boil water” and a “big mama’s boy.”

"It was one of a kind," Philonise said of his brother's relationship with their mother. "It was so unique how they were with each other."

Through Philonise’s testimony, jurors were given a glimpse at who George Floyd was decades before his name became a headline around the world. Philonise smiled and cried each time as as prosecutors showed pictures of George as a young child in his mother’s arms, at a desk as a high schooler in Texas and in a basketball jersey with South Florida community college teammates.

An young George Floyd is seen being held by his mother. The photo was shown as an exhibit Monday, April 12, 2021, in Hennepin County District Court.
An young George Floyd is seen being held by his mother. The photo was shown as an exhibit Monday, April 12, 2021, in Hennepin County District Court.

Defense could begin its case Tuesday

Before jurors were brought into the courtroom Monday morning, Nelson requested the jury be sequestered before deliberations began and to re-question the jurors following the fatal police shooting of a 20-year-old man in Brooklyn Center, Minn., Sunday afternoon, April 11, during a traffic stop. Special Assistant Attorney General Steve Schleicher opposed the motion. Judge Daunte Wright ultimately denied the defense's request.

The death of Daunte Wright prompted protests Sunday night that turned into violence. Gov. Tim Walz on Monday set a curfew in several Metro counties as a precaution against any civil unrest.

The Chauvin jury recessed around 4:30 p.m. Monday with notice from Judge Peter Cahill that the defense would likely begin its case sometime Tuesday, April 12. Jurors were also told that closing arguments would come Monday, April 19, and with it the sequestration of the jurors would also begin. Jurors will be sequestered until a verdict is reached.

Correction: Due to an editing error, Philonise Floyd's name was wrong in a reference in an earlier version of this story. This story has been updated with the correct name. We regret the error.