Defenses- Rising Blood Alcohol

Rising Blood AlcoholRising Blood Alcohol Defense

What is the rising blood alcohol defense and how can you use it to defend yourself if you are accused of a DUI?

Before we begin, let’s review the law. In California, it is against the law to DRIVE under the influence of alcohol or to DRIVE with a BAC of 0.08 or higher. Evidence that your BAC was a 0.18 at the time your were tested is not the same as evidence of your BAC at the time you were driving.

So the issue always is, what was your BAC at the time of your driving?

Let’s start by discussing how alcohol is absorbed by the body and then eliminated. Alcohol, in order to produce its intoxicating effect, must find its way to the brain after you ingest it. To accomplish this, it finds its way into your blood through the walls of your stomach and through your lower intestines. This absorption occurs through the simple biochemical process of “diffusion”. This diffusion process will continue as long as the concentration of alcohol in the stomach and the intestines is higher than that in the blood. We call this absorption of alcohol into your body (and your brain) the “absorption process.”

How long does this “absorption” process continue? Most studies indicate that it can start in as little as five minutes and be completed between 20 minutes and an hour and a half, depending on your own physiogamy, the kind of drink that you had, whether or not you ate, how fast your eliminate alcohol (your “beta” factor or “burnoff rate”), your weight, your gender, when you started drinking, when you stopped and your ratio of total body mass to total body weight (your “R” constant).

As soon as alcohol is completely absorbed by the body you hit a “plateau”. Then the burnoff process begins. Most crime lab toxicologists and criminalists (the ones who will be testifying against you) will claim that an average burnoff rate is approximately 0.015/hour. Note the words “average” and “approximately”. The bottom line, and you can quote me on this, is that retrograde extrapolation is nothing more than an educated guess, and not a very good one at that. There are simply too many factors that cannot be nailed down to give you any meaningful number.

Looking at the graph below, the first thing to note is how quickly alcohol is absorbed and how slowly it is eliminated from the body. If your BAC is falling faster than 0.015 an hour, you have a right to be suspicious of the BAC results. On the other hand, if it is rising rapidly, you are almost certainly in the absorption phase.

I recently had a case where my client was stopped at 2 am, gave a PAS breath test at 2:20 and blew a 0.09. By 2:45 she had a BAC of 0.13. In a twenty five minute period of time her BAC rose by 0.04. That means that when she was driving her BAC could have been as low as 0.05 or even lower. On this basis alone, she was acquitted.

On the other hand, it is universally conceded that when you are eliminating alcohol, you will be doing so slowly. The concensus among most prosecutors is that you eliminate alcohol at a rate of 0.015/hour, but this is only an average. Some people have metabolisms that will allow them to eliminate alcohol rapidly, others do not.

Regrograde Extrapolation

The most obvious way to determine your BAC at the time of driving is to use a process called “retrograde extrapolation”. Retrograde extrapolation basically uses trend lines to determine (a) if your blood alcohol level is rising or falling and (b) to determine what it would have been at an earlier point in time based on the assumption that your BAC is either rising or falling.

The basis for retrograde extrapolation is a controversial formula—in use by every district attorney in the country—called the “Widmark Formula”. Without going into the details of this formula, for some reason D.A.s love it even though it is really easy to destroy during a trial. The problem with the formula are the variables. There are too many of them, and you cannot nail them down with averages.  Put simply, these numbers are useless.  You cannot make any meaningful extrapolation of what your BAC was at an earlier point in time with only two samples and a list of variables any one of which could screw up the results.

What the D.A. will argue

As a general rule, expect the district attorney to argue that you are in the elimination phase (falling BAC) of alcohol since that means that your BAC was higher when driving than when you did your breath or blood tests. Ergo, your BAC was even higher than when you tested. Of course, defense attorneys are usually hoping for the opposite—rising blood alcohol indicates that you have a lower BAC when you were driving.

The simple fact is that few district attorneys understand retrograde extrapolation, the Widmark Formula or how alcohol is absorbed or eliminated. What they seem to be persuaded by are simple numbers. So use them when it helps you to do so.

The bottom line is that if your BAC was rising rapidly between the roadside breath test and the breath or blood test at the station, see how rapidly it rose and from what number. If you can show that your BAC was significantly lower at the time of driving (hopefully you were close to home when you were stopped) then you could negotiate a reduction in sentence or even obtain an acquittal.