Derek Chauvin is on trial for George Floyd's death

By Mike Hayes, Melissa Mahtani and Meg Wagner, CNN

Updated 0406 GMT (1206 HKT) April 16, 2021
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11:53 a.m. ET, April 15, 2021

CNN analyst: Jury was not present during conversation about new carbon monoxide test evidence 

From CNN's Laura Coates / Written by CNN's Maureen Chowdhury

The jury was not present during discussion about the prosecution potentially introducing new evidence about George Floyd's carbon monoxide blood levels, legal analyst Laura Coates explained. Judge Peter Cahill ruled that the prosecution cannot use this new evidence in their rebuttal case.

"That seed of reasonable doubt has not been planted," she said.

"Here's the thing. You and I and all of us are in the court of public opinion, not in the courtroom. That entire transaction just now, that exchange, did not take place in front of the jury. So the jury does not know that this has now happened. It is a good thing for the prosecution and also a good thing for the defense if they believe, that of course, this data that undermines their theory," Coates said.

The judge reached a compromise with the prosecution that they can discuss George Floyd's oxygen levels instead, but they cannot bring up the test results at all or a mistrial will be ruled.

"Judges don't want to give the prosecutors two bites at the apple. They don't want redundant testimony. If you could have raised it earlier, you should have, you had the chance, sit down. This time the prosecution is saying that when Dr. Fowler raised the issue of carbon monoxide poisoning, and although we had some semblance of what the theory might be, you presented some new theories, 'So, we're not asking for a second bite of the apple, Your Honor, we want a first bite of at the apple based on this new theory.' The problem is the prosecution made a mistake. They did not take seriously the thought of carbon monoxide poisoning as potentially being a viable claim to be raised by this doctor. They may have overlooked the data and did not present it through their own witnesses to rebut and preempt this," Coates continued.

11:56 a.m. ET, April 15, 2021

Pulmonologist says defense witness is "simply wrong" on Floyd’s carbon monoxide level

Dr. Martin Tobin, left, testifies on Thursday, April 15. Dr. David Fowler, right, testifies on April 14.
Dr. Martin Tobin, left, testifies on Thursday, April 15. Dr. David Fowler, right, testifies on April 14. Pool

Dr. Martin Tobin, a pulmonologist, said during rebuttal testimony that the opinion of defense expert witness Dr. David Fowler regarding George Floyd's potential level of carbon monoxide in his blood was "simply wrong."

Tobin said medical records showed Floyd's oxygen saturation was 98% when he died. Prosecutor Jerry Blackwell asked him: "Does that tell us anything whatsoever about what the carbon monoxide content could have been at a maximum?" 

Tobin said: "Yes, it does. It tells us that if hemoglobin is saturated at 98%, it has – for others is 2%. So the maximum amount of carbon monoxide would be 2%." 

Why this is important: Dr. Fowler testified that it was possible that carbon monoxide ingestion could have been one of the causes of Floyd's death. He based this on observations of Floyd being pinned on the ground near the tailpipe of the police cruiser that officers were trying to get him into. Fowler acknowledged that he had not seen any data on Floyd's carbon monoxide levels prior to testifying.

During his testimony Fowler said that it was his opinion that Floyd's carbon monoxide levels in his blood could have increased by 10% to 15%. Tobin said that assessment is "simply wrong."


11:44 a.m. ET, April 15, 2021

Dr. Tobin has to be "on the shortest, tightest leash possible" to prevent a mistrial, CNN analyst says

From CNN's Aditi Sangal

As the prosecution recalled Dr. Martin Tobin as a rebuttal witness at the Chauvin trial, CNN legal analyst Laura Coates says the pulmonologist will have to be on the "on the shortest, tightest leash possible" to ensure the judge does not declare a mistrial.

Tobin previously testified that it was his opinion that George Floyd died from low oxygen levels, and he will now be rebutting the testimony of defense expert witness Dr. David Fowler, a retired forensic pathologist.

"The judge has been very clear he will declare a mistrial because any hint, any suggestion or mention of the Hennepin County data will be prejudicial to a defendant who gave notice through their witness expert about a theory of carbon monoxide poisoning. And they did not have the data disclosed to them in time to be able to potentially fully flush it out or to recoil on their own theory," Coates explained.

She added:

"Appellate courts have no tolerance for prosecutors who do not disclose information in a timely fashion and try to get it through a rebuttal witness. And so, this prosecution team is going to have to be extraordinarily prudent. And I hope that this witness, as informative as he is, can stay ton that leash."

The risk is that witnesses can be like wild cards, just like jurors, Coates explained.

"I don't care if you are the most seasoned expert testifying witness. Sometimes they do not understand the implications of their slip-ups or making a statement ... Defense attorneys are always on guard with this very point," she said. "In the event of a conviction, they want to have their ducks in a row of how they can seek an appeal to overturn based on, especially, prosecutorial misconduct or any allegations based on that."

11:27 a.m. ET, April 15, 2021

The prosecution recalls pulmonologist as a rebuttal witness

Dr. Martin Tobin testifies on Thursday, April 15.
Dr. Martin Tobin testifies on Thursday, April 15. Pool

The prosecution has called Dr. Martin Tobin, a pulmonologist, as a rebuttal witness at the Chauvin trial.

Tobin is rebutting the testimony of defense expert witness Dr. David Fowler, a retired forensic pathologist.

Tobin previously testified that it was his opinion that George Floyd died from low oxygen levels.

11:24 a.m. ET, April 15, 2021

The defense rests its case


Defense attorney Eric Nelson just rested the defense's case in the Derek Chauvin murder trial.

Prior to that, Chauvin declared in court that he would invoke his Fifth Amendment privilege and not testify.

What happens next: The prosecution is expected to call one rebuttal witness today.

11:03 a.m. ET, April 15, 2021

Judge says he will declare a mistrial if prosecution witness "even mentions" carbon monoxide blood tests


After the defense rests its case, Judge Peter Cahill will allow the prosecution to call a witness to rebut some of the testimony by defense expert witness, Dr. David Fowler. But the judge said that he will limit what the witness can testify about.

During a court proceeding this morning prior to the jury coming in, both sides argued over the rebuttal testimony.

Prosecutor Jerry Blackwell told the judge that the prosecution had new evidence to present regarding carbon monoxide in George Floyd's blood. Yesterday, Dr. Fowler, a retired forensic pathologist, said it was possible that carbon monoxide ingestion from the tailpipe of the car that Floyd was pinned on the ground near could have contributed to his death.

Defense attorney Eric Nelson said he opposed allowing the prosecution to present this evidence and call its rebuttal witness. Nelson argued that the disclosure of these new test results was untimely. He said that he only received the information last night after court had wrapped for the day.

The prosecution indicated in court that the witness they will call to rebut Fowler's testimony is Dr. Martin Tobin, a pulmonologist that testified at trial that Floyd died of "low oxygen levels."

The judge ruled that Tobin can testify however, he is not allowed to tell the jury about the test results. He said that any mention of these records will result in a mistrial.

10:35 a.m. ET, April 15, 2021

Chauvin just invoked his Fifth Amendment right. Here's what the Constitution says.

Moments ago, Derek Chauvin told the court he would not testify in his own defense in the George Floyd murder trial. 

Chauvin invoked his Fifth Amendment right when he chose not to testify.

According to the White House, the Fifth Amendment "provides that citizens not be subject to criminal prosecution and punishment without due process."

Here's the full amendment:

"No person shall be held to answer for a capital, or otherwise infamous crime, unless on a presentment or indictment of a Grand Jury, except in cases arising in the land or naval forces, or in the Militia, when in actual service in time of War or public danger; nor shall any person be subject for the same offence to be twice put in jeopardy of life or limb; nor shall be compelled in any criminal case to be a witness against himself, nor be deprived of life, liberty, or property, without due process of law; nor shall private property be taken for public use, without just compensation."
10:35 a.m. ET, April 15, 2021

Why Derek Chauvin may not want to testify, according to a CNN analyst

From CNN's Aditi Sangal


Ex-Minneapolis Police officer Derek Chauvin just said he will invoke the Fifth Amendment and not testify at his murder trial.

"It's not all that shocking to think that he would not want to open himself up to the prosecution," CNN legal analyst Laura Coates explained. "A lot of things can come in when you take the stand, including your past prior bad acts, any allegations and misconduct that have been cleared by the judge. And, of course, you risk the very, you know, foreseeable aspect of it that you cannot defend your actions. And all you leave to the jury is this impression of you as somebody who has committed this crime."

The defense also does not have the burden of proof, she added.

"He never had the burden to prove his innocence. It always remained with the prosecution. And now, the jury will be instructed, per his request, that they are not to draw any inference from his decision not to testify," Coates explained.

10:53 a.m. ET, April 15, 2021

Chauvin chooses not to testify


Defense attorney Eric Nelson just explained to his client that he has the right to testify at the trial. Derek Chauvin just said that he will invoke the Fifth Amendment and not testify.

Here was their exchange:

Nelson: Have you made a decision today, whether you will attempt to testify, or whether you intend to invoke your Fifth Amendment right? 

Chauvin: I will invoke my 5th amendment privilege today. 

The judge then asked Chauvin if the decision was his. He said it was.

See the moment: