Alcohol estimate method criticized
Used when driver’s blood test is delayed
CENTRAL ISLIP, N.Y. — The way prosecutors see it, Oneil Sharpe Jr. was drunk when he raced down a Long Island highway at nearly 100 mph this summer and slammed into a car carrying a family home from a church gathering, causing a fiery wreck that killed a father and his two children.
Sharpe’s blood-alcohol reading, taken about four hours later, was 0.06 percent — below the legal threshold of 0.08. But he was still charged with drunken driving and vehicular homicide because a forensic technique estimated that his blood-alcohol level at the time of the crash was 0.12.
That technique, known as “retrograde extrapolation,” has been used to win convictions nationwide for decades but has increasingly come under scrutiny by drunken-driving experts as an unreliable measure of a person’s intoxication.
“Government lawyers and puppet scientists know retrograde extrapolation is hogwash and will say so when it benefits them, but mostly they pretend otherwise because it is useful in gaining convictions,” said D. Timothy Huey, a Columbus, Ohio, attorney specializing in drunken-driving cases.
While there are no national statistics to document the use of retrograde extrapolation, prosecutors in many states, including New York, North Carolina, Michigan, Colorado and Illinois, have offered evidence of estimated intoxication levels at trial. But courts in some other states have severely restricted its use, requiring prosecutors to use only the blood-alcohol readings taken at the time of a person’s arrest.
Prosecutors who have used retrograde extrapolation swear by it as a proven technique that doesn’t reward drunken-driving suspects for fleeing the scene and avoiding immediate blood-alcohol testing.
“It’s been standard procedure for many years in many states across the country,” said Beadle County, South Dakota, State’s Attorney Michael Moore.
Experts say the intoxicating effects of alcohol are not experienced until it is absorbed into the bloodstream. After a person stops drinking, the blood-alcohol level peaks when the most alcohol has been absorbed and the least amount of alcohol has been eliminated.
Defense attorneys argue alcohol absorption and elimination rates vary widely depending on a person’s gender, drinking habits, the type of beverage, what a person ate and how much and whether a person had experienced trauma, which sometimes slows the rate.