BrAC --> BAC. OK, what does this mean you ask? This is just a simple symbol for the breath alcohol to blood alcohol conversion that the State's breath testing equipment must perform. Maine uses an Intoxilyzer 5000EN to analyze your breath sample. However, obtaining a breath alcohol concentration is not enough because Maine law calls for a blood alcohol concentration. Therefore, the Intoxilyzer must convert your numeric breath alcohol concentration into a blood alcohol concentration.
Partition Ratio & Henry's Law. What the heck are you talking about now? Henry's Law in its most simplified format says that when you heat a solution w/alcohol to a specific temperature (in a jar), that alcohol in the solution will be found in a gaseous state above the solution at a fixed partition ratio of 2100:1. That means that the alcohol found in the solution is 2100 times more concentrated than the alcohol above the solution. Needless to say, the people who created the Intoxilzyer 5000EN want everyone to believe that you and I are just like glass jars... 'nuff said.
Retrograde Extrapolation. Am I losing you? Retrograde extrapolation is the junk science (well, in all fairness, it is a legitimate scientific exercise that can determine your BAC at a certain place in time but only when issues such as weight, type of alcohol consumed, number of drinks, time started, time finished, and many other factors are known to a certainty by the State) employed by the prosecutor and his/her expert witness to go back in time to determine your blood alcohol content at the time of driving.
It's the State's burden to prove beyond any reasonable doubt that at the time you were driving, you were either impaired to the slightest degree by alcohol or that your blood alcohol content was .08% or greater. They attempt to achieve this by employing a complicated equation commonly referred to as the Widmark Formula. Of course they must assume for purposes of scientific validity that you were in the elimination phase rather than the absorptive phase (ie, you had already completely absorbed the alcohol into your blood stream and the body is now working to eliminate the alcohol). Now do you understand why they ask you all those crazy questions about how much you had to drink, when you ate, what you ate, where you ate, etc.? Because they're going to use that information against you later to establish a timeline so that the State's expert can reliably perform a retrograde extrapolation.
It's the State's burden to prove beyond any reasonable doubt that at the time you were driving, you were either impaired to the slightest degree by alcohol or that your blood alcohol content was .08% or greater. They attempt to achieve this by employing a complicated equation commonly referred to as the Widmark Formula. Of course they must assume for purposes of scientific validity that you were in the elimination phase rather than the absorptive phase (ie, you had already completely absorbed the alcohol into your blood stream and the body is now working to eliminate the alcohol). Now do you understand why they ask you all those crazy questions about how much you had to drink, when you ate, what you ate, where you ate, etc.? Because they're going to use that information against you later to establish a timeline so that the State's expert can reliably perform a retrograde extrapolation.
These are just three of many issues involved in OUI cases and merely serve as an example of the complex science involved in the prosecution and defense of these cases. I barely even scratched the surface here but I think you get the idea. When it's time to retain an attorney to defend your OUI case, make sure he or she has at the very least, a basic understanding of the science involved in these cases. It's just not enough to know the law.
William T. Bly, Esq.
Maine OUI Lawyer
