Professor Kenneth Ferslew using whiteboard
photo by Joseph Dycus
Two toxicology experts in Judge Barry Steelman’s courtroom expanded on the topic of retrograde extrapolation during Justin Whaley’s motion hearing on Monday. Whaley is facing vehicular homicide charges after his vehicle crashed into another car and claimed the lief of James Brumlow in 2018. Whaley was allegedly intoxicated during the incident; however, a blood draw was not taken until four hours after the crash.
The former EMT was arrested after the wrong-way crash on Highway 111 on July 3, 2018.
Because of this, the state had to extrapolate based upon the results, which led them to charge him with driving under the influence. Defense attorney Lee Davis has asked for the results of the blood draw to be suppressed, saying that level of extrapolation is unreliable and should not be admitted as proof. Prosecutor Christ Post brought in ETSU professor Kenneth Ferslew of the William L. Jenkins Forensic Center to discuss why the blood draw results should be admitted.
“If we believe the story, he was drinking from 9 p.m. to midnight or 1 a.m. in the morning, according to the evidence you’ve provided to me,” Professor Ferslew said. “So then he went to bed, then woke up and drove to the event. So the event is at 5:40 in the morning. I’ve got four additional hours in there after the drinking event. We’re in elimination by all studies I’ve ever seen, since we’re way past where maximum absorption has occurred.”
The witness said that the body begins breaking down and processing alcohol from the moment it enters the body, but that as a person drinks, the amount of alcohol being broken down is outpaced by the amount coming in. When people drink more, then that’s when their blood alcohol content goes up. But after alcohol is no longer consumed, then the blood alcohol level goes down in a linear fashion. The professor used a whiteboard and markers to illustrate his point.
However, after a certain level, the decline in alcohol is no longer linear. For the TBI, that level is 0.02 gram percent concentration. Professor Ferslew told Judge Steelman that if the police had waited even 15 minutes longer, then the results would have been unusable. As it stands, the results of the draw were right on the border of what is admissible.
“They are 99.73 percent confident by statistical analysis that blood has a 0.02 gram percent concentration in it,” the expert witness said. “The variation, or measurement uncertainty, is in the third decimal at 0.002, so if you want to take the uncertainty and calculate it in, that means 99.7 percent of 100 measurements go from a range of .0198 to .022. That’s why they report to that low number and now lower.”
By operating under the assumption that the level was at 0.02 percent at the time of the draw, the TBI used retrograde extrapolation to figure out that Whaley was intoxicated when the crash occurred.
“Your previous testimony was had the police taken this blood sample taken 15 minutes later, in your opinion this would have been reported as a negative,” attorney Davis said. “So we’re right on the very line of what is reportable.”
Attorney Davis then brought on his own toxicology expert, who disagreed with the prosecution’s decision to use the blood draw as evidence. Jimmie Valentine believes that once a person’s BAC levels were that low, then one could not draw results from it once information was extrapolated.
“What he’s talking about is when you get into this non-linear portion, if you’re at 0.02, you’re alright,” Mr. Valentine said. “I don’t agree with that. I think that when you get into these really low BAC levels, you’re in the non-linear portion of the curve. So what happens when you try to to any retroactive extrapolation, it’s just a wild guess at that point. You’ve either overestimated or you’ve underestimated, and you just don’t know.”
The defense also had issues with the state not knowing the precise amount of alcohol Whaley consumed that night. Witness testimony said the defendant had consumed six glasses of various kinds of bourbon. However, those glasses were anywhere from one to three ounces.
Mr. Valentine told the court that just having one sample taken at such a murky time was not “scientific.” He said that in other states, two or even three samples are taken over the course of several hours.
“If we give the benefit of the doubt, he’s below 0.02, so that puts us right in this non-linear portion of the curve,” Mr. Valentine said. “Using this retrograde extrapolation is just not very scientific at this juncture. It’s best used when you have multiple samples from different times, so you can be sure.”
The two experts argued with one another over this idea, but in the end the judge decided he would need time to review what was said before coming to a decision.
“It was very helpful testimony today from both sides, and it was very educational to the court,” Judge Steelman said. “It was a privilege, really, to hear such learned individuals in this field. We’ll try to decipher it and make a decision about what the jury will hear on Sept. 21.”