Factors That Effect Breath Test Results

Instead of a dry, boring article, the following is an excerpt from a recent interview with Attorney Leckerman on the subject.

Interviewer: When someone gives a breath test and the result is .08 or higher or lower, I’m sure there’s a lot of factors that, let’s say a 300 pound man who drank X amount, would blow very differently from a 120 pound woman. So, in your experience, what are some of the factors that can affect the results of a breath test, either high or low?

Kevin Leckerman: You bring up physical condition. That is definitely a primary factor which can affect breath test results. Now, in some states, there have been decisions rendered by courts, essentially establishing an average physical state that is taken into consideration when converting someone’s blood alcohol concentration to breath alcohol concentration. What I mean is the breath testing technologyis premised on the fact that human beings will exhale a certain number of alcohol molecules, in comparison to the number of alcohol molecules that is in that person’s blood.

Of course, each human being is totally different. Each human being is different physically. No two people will be exhaling the same amount of alcohol in each breath sample, even if those two people have the same amount of alcohol in their blood. So, the science behind the devices assumes that there’s a particular amount of molecules of alcohol that will leave the bloodstream, pass through a barrier that separates the blood stream from the lungs, and goes through that barrier into the lung air. This is called a partition ratio. This partition ratio is accepted in most states as being 2,100 to 1. So for every 2,100 molecules of alcohol in a person’s blood you’re going to get one molecule of alcohol in a person’s breath sample.

Interviewer: So, what happens if someone is arrested and they’re at the police station and they have to give a breath sample and they drank 45 minutes ago versus two hours ago, versus four hours ago. Are there any defenses because of how recently they drank alcohol, and how will that affect a breath test?

Kevin Leckerman: In New Jersey there is no specific rule of law that requires a police officer to administer a breath testing device within a certain period of time, from when the person was driving the vehicle. Generally speaking, the case law states that a reasonable period of time is before three or four hours after someone’s driven a vehicle. It seems a bit ridiculous that somebody can be punished for the amount of alcohol that’s in his system three to four hours after driving a car. However, the courts have rationalized this rule of law in stating that they don’t want to encourage someone to essentially guzzle a huge amount of alcohol and then jump in a car and race to get home before their blood alcohol level gets to the legal limit.

In Pennsylvania, there is a standard two hour period of time wherein the officer has to take blood or breath or urine from the time of the operation of the vehicle. There can be exceptions that would allow the blood alcohol results to come into evidence. Those exceptions have to do with some extenuating circumstances that were beyond the officer’s control.

Interviewer: Is there any defense where let’s say someone just finished their last drink. They drank fast and drank three beers in 20 minutes. They got in the car and drove home and they were pulled over and asked to take a breathalyzer. At that point, in their bodies, a lot of the alcohol would still be in their stomach, not in their breath. Is there any rising or falling of the blood alcohol defense because of the recency of which they’ve had alcohol, or no?

Kevin Leckerman: In Pennsylvania, there is this two hour rule that’s been established by law. So, as long as the person’s tested within two hours, that final blood alcohol concentration is something that cannot be disputed based on what you’re referring to as “retrograde extrapolation.” However, there is some distinction in the law that allows a person to bring that issue into play, in order to challenge the charge of being generally impaired. This is getting a bit technical.

But if you can show that there may be some type of issue with the breath test or blood test results, you can also try to utilize that information in order to create a defense that the person did not have a specific blood alcohol concentration at the time he or she was driving.

In New Jersey, you are not allowed to use retrograde extrapolation, in order to bring into dispute the breath test reading or the blood test reading. There is one exception. When you can call into question the breath test or blood test readings, because there is some other defense to those readings, such as reflux disease or diabetes, then a defense lawyer then can try to utilize this retrograde extrapolation as a method to scientifically show the person could not have been under the influence at the time he was driving.

The retrograde extrapolation equations are very technical. Some scientists certainly don’t believe that they can accurately determine one’s blood alcohol concentration. Moreover, a lot of the information that’s utilized in trying to do this retrograde extrapolation is based on the driver’s subjective recitation of what occurred that night. So, the main factor to that equation would be what type of alcohol the driver drank, how much of it, and over what period of time. If that can be established objectively, through credit card receipts, eyewitnesses or maybe video tape, then it becomes more believable.