Breath Alcohol Analysis Expert Weighs In On Accuracy of Delayed Breathalyzer Readings

Victoria Negron

Written by
— Updated on February 28, 2018

Breathalyzer Expert

This case involves a man who was pulled over for speeding on a major thruway. He was administered a ticket but no breathalyzer reading was recorded. Several hours later, the same man was arrested for disorderly conduct in a residential area. At the time of arrest, the man had a breathalyzer reading of 0.09. It was alleged that the man’s blood-alcohol content at the time he was pulled over was higher than the breathalyzer reading at the time of arrest. An expert was sought to opine on the appropriate protocol for taking breathalyzer readings and the accuracy of a reading taken after several hours.

Question(s) For Expert Witness

  • 1. Please describe your background as relates to breathalyzer reading accuracy/protocol.

Expert Witness Response E-172780

I have served as an expert witness on countless DUI cases in New York courts and have published and lectured on the flawed nature of breath-alcohol analysis. A breathalyzer reading taken several hours after the initial stop cannot be used to demonstrate the individual’s blood alcohol content when they were first stopped. Often times the prosecution will argue that if the individual blew a 0.09 on a breathalyzer five hours after the stop, their blood alcohol content had to have been higher at the time of the initial stop, but this is definitely not necessarily true. I have published research on retrograde extrapolation and its unreliability. Additionally, how many times the individual blew into the machine and if the mouthpiece was changed after each blow should be looked at.

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