The Hidden Danger of “One for the Road”

Posted by Lawrence Taylor on June 8th, 2008

In previous posts, I’ve explained many of the reasons why breathalyzers are inaccurate and unreliable. See, for example, “Breathalyzers — and Why They Don’t Work“; ”Warning: Breathalyzer in Use“; ”Convicting the ‘Average’ DUI Suspect“; “Why Breathalyzers Don’t Measure Alcohol“; “Driving Under the Influence of… Gasoline?; ”How to Fool the Breathalyzer“. (These and many other sources of error are explained more fully in Chapter 6 of my book, Drunk Driving Defense, 6th edition.)

One of the most common sources of error in breath alcohol analysis is simply testing the subject too early — while his or her body is still absorbing the alcohol.

Let’s take a common example. At a restaurant Sarah shares a bottle of wine with a friend. She nurses one glass over a one-hour dinner. Nearing the end, another glass is poured from the bottle and she finishes this. The two friends then order an after-dinner drink. Noting the time, Sarah quickly finishes the drink and leaves. She is stopped by the police one block from the restaurant. After questioning and field sobriety tests, she is taken to a police station and tested on a breathalyzer. The machine shows her blood alcohol concentration (BAC) to be .09% — over the legal limit. She is booked for DUI and jailed.

Sarah’s true BAC, however, was lower, perhaps much lower. If a blood sample had been taken instead of a breath test, the results would have shown only .05% — well under the legal limit.

Absorption of alcohol continues for anywhere from 45 minutes to two hours after drinking or even longer. Peak absorption normally occurs within an hour; this can range from as little as 15 minutes to as much as two-and-a-half hours. The presence of food in the stomach can delay this to as much as four hours, with two hours being common.

During this absorptive phase, the distribution of alcohol throughout the body is not uniform; uniformity of distribution — called equilibrium – will not occur until absoprtion is complete. In other words, some parts of the body will have a higher blood alcohol concentration (BAC) than others. One aspect of this non-uniformity is that the BAC in arterial blood will be higher than in veinous blood (laws generally require blood samples to be veinous). During peak absorption arterial BAC can be as much as 60 percent higher than veinous.

This becomes very relevant to breath alcohol analysis because the alveolar sacs in the lungs are bathed by arterial blood, not veinous: The diffusion of alcohol through the sacs and into the lung air will reflect the BAC of the body’s arterial blood. Therefore, the breath sample obtained by the machine will be reflective of pulmonary BAC — which, during absorption, will be considerably higher than veinous BAC (and higher than the BAC in other parts of the body).

After extensive research, one of the most noted experts in the field of blood alcohol analysis has concluded:

Breath testing is not a reliable means of estimating a subject’s blood alcohol concentration during absorption…..

There is a significant likelihood that a given subject will be in the absorptive state when tested under field conditons. Because of large differences in arterial BAC and veinous BAC during absorption, breath test results consistently overestimate the result that would be obtained from a blood test — by as much as 100% or more. In order to have some idea of the reliability of a given breath test result, it is essential to determine by some objective means whether the subject is in the absorptive or post-absorptive state. In the absence of such information, an appropriate value for the uncertainty associated with the absorptive state should be applied to all breath test results.

Simpson, “Accuracy and Precision of Breath Alcohol Measurements for Subjects in the Absorptive State”, 33(6) Clinical Chemistry 753 (1987).

The most recognized expert in the field, Professor Kurt Dubowski of the University of Oklahoma, agrees with Simpson: “When a blood test is allowed, an administered breath test is discriminatory, because in law enforcement practice the status of absorption is always uncertain.”

  • jim

    I just spent the morning reading about 20 DUI appeal decisions fron the NJ Law Division and Appealate Courts.
    I could not find one reversal.

    It really doesnt matter how many mistakes police made, if evidence is destroyed, is the science is accepted or not, if the trial was speedy, …. nothing matters.
    Once a municipal court judge finds you guilty of DUI, thats it, and the Judge can do that without regard to the law or evidence, because the Law Division and Appealate Courts will back him up 100 percent of the time, simply by saying the appeal has no merit.

    It is really shocking to me that this is the case. I had no idea I was so niave to this.

    I am completely shattered and disallusioned.

    That being said, ill be making my 15th court appearanceover 33 months time, for a lowest level first offense DUI, THAT i ALWAYS THOUGHT ii COULD WIN BASED ON THE FACTS AND THE LAW, BUT PROBABLY CANT WIN, BASED ON HOW THE JUSTIC SYSTEM REALLY WORKS.

    That being the case, not only have I lost almost 3 years of my life so far, I am going to lose the DUI case , if and when it even gets to trial in front of a municipal court judge.

    there are no jurys for DUI in nj, it is not considered a crime. All that needs to happen is for a local prosecutor to enter the evidence on the record, have the officers testify, and have ajudge rule on guilt. it is not tooo complicated a process that I should be sitting here 3 years later making my 15th court appearance for it.

    the whole situation sucks.

  • jim

    one for the road– no at all a good idea, especially in new jersey, where there is traffic all the time, and police everywhere.

    getting back to my point–
    in new jersey, and probably california too, most run of the mill, non accident dui cases, are heard and trialed in the hallway between the prosecutor and defense attorney, and if sometrhing was really wrong about the arrest, the cases gets dropped, otherwise the defense attorney has to try to convince why the defendant deserves a break and save everyone time and money, and reduce the charge, or drop the case.

    while this is probably never going to be ended, as it is pary of typical initial discocery meetings, it should not go on indefintively out 33 months and 15 appearances, and longer.

    at some point, way earllier than that point, the case needed to go to trial and let a judge decide.

    the problem in nj is that municipal courts do not have the time/resources to hold dui trials, as they rake in 200k a week for speeders.

    it is an appauling situation, that is swept under the carpet by most americans, who do not understand, when the rights of an individual are violated, everyones rights are violated.

    this musat start in our communities on a grass roots level and filter all the way to federal government.

  • joe

    The rigid rules put in place are so silly, they make it easy for the police and courts to bring about arrests and convictions (thus making them look good publicly) but do little to serve justice or to give proper guidelines. How are people supposed to know what they can and cannot drunk at a restaurant with dinner, it’s as if the law wants them to carry calculators to determine their body weight index with ever sip of wine they take.

  • jim



  • jim

    joe- the law for dui in nj says a person with a blood alcohol concentration by weight is 0.08% or greater, he is dui. thats the “rule”.
    it says nothing of breath testing to estimate it.

    every dui case should have blood taken, taken by a validatred method by validated personel, tested with a vaildated method, on a validated gas chromatoraph, with split samples being taken in a validated way, sealed with no head space, and sent to a 2nd certified lab for validated testing.
    eliminate all observation convictions, make every case a win or lose or the per se violation.

    lawyers under this system would be allowed to audit labs, and have all validation documentation.

    the defenses are many to any analytical result, believe me, ive been an analytical chemist for 20 years in several areas.

    however, everything right, there should be no problem in the result.

    guilty or not guilty, would be clear.

    now, a result like this, all comes down to error. error can be found in many forms, but at least it would not be an estimate of bac using breath, it would very pretty much a right on number, given everything was done right.

    usually, an internal standard would be used in the methods, isopropyl alcohol, because gc is tricky that way with responses. especially for forms of alcohol.

    the result would encompass the actual chromatograms of stands and sample injections, the signal counts from each, the standard/internal standard ratios, the sample/internal standard ratios, and the final result.

    everything would be there for review, including maintanance logs for the gc, validation of the method and instrument, operator certification, trhe whole bit.

    and thae law, and judges, just as the fda would, should say that the rewsult is invalid, if any one thing was done wrong.

    i am talking about striving for and achiewving perfection

  • jim

    now there is still grey area in this as well, political grey area.
    if someone is afraid of neddles, they should have the choice for a breath test, but the first course of action would be a blood test.

    2nd, any refusal for testing at all, would be grounds for the refusal summons, which is just like a dui in penalty, very similair.

    3rd- under this new way of doing thing i propose, police officers would have to use their heads as to whether or not they want to make a dui arrest , and get a blood tst, on boarderline cases.

    the fact is, using breath testing opens the door for the kind of hall way trials, that are sometimes prolonged, that never benefit the defendant if prolonged.

    justice is not something that should be pulled out of thin air.

    read my post above as well.

  • jim

    let me put it another way, if i had 2 or 3 drinks at a bar for luinch, was pulled over 5 minutes later, was given a breath terst that said 0,08% bac, how the hell can i know or anyone actualkly know if my blood alcohol content, as per the statute requirement, was at 0.08% bac.

    as a defendant i must plead not guilty, because how would i know for sure if i was guilty or not?

    i couldnt possibly, and neither could anyone else.

    just a hypothetical.

    the circumstances of my case do not reflect this hypothetical situation , but for the fact i blew a 0,08 bac on a breath test.

  • koivisto

    Using an arbitrary number is great for the police, but doesn’t take into consideration the actual condition of the driver. I understand you have to have a criteria to go by, but again, guilty until proven innocent is insane. The only people who are crying foul are in such a minority that their voices will not be heard. I’m afraid that the laws will only get worse and there is nothing that can be done. After my foray into the justice system, I now have my wife drive me if I even have one drink because I fear what may happen. Welcome to amerika. In the meantime, drugs are spilling over the borders, as well as illegal immigrants. The dollar is dropping, were conducting an illegal war, and people are starving around the world. Lets go fight the evil drunk drivers!

  • jim

    what i dont get is why not just make a law that fixes the problems, convicts the guilty, and aquits the innocent?

  • koivisto

    If they did that then they wouldn’t have the money coming in. Please realize how many people get fines even if they weren’t DUI. If they fixed it they would not have the cash flow. Besides DUI arrests are good for the officers career, not the conviction rate.

  • Justin

    As I understand it — most .08 cases tended to get pleaded down to reckless, inattentive, withheld judgment, or nolle prosecution.

    The inherent error in most machines are at least .01 and even the “expert” on the side of the police will admit this in front of a judge.

    .089 and below could be .079 and that is reasonable doubt. If they can get you convicted on a lesser charge that pays a fine ranging from 300-2500 dollars and make you renew your license which might costs another 100-250 and get you on a high priced insurance for 2-10 years which will cost you 300-1300 annually. Why not take your money? Not to mention if you want to get a “good” “non government” job (since you’ll probably get a misdemeanor and that means no chance at being an agent of the gov. if you plead) you’ll have to get an expunging done to your record. Cha-ching.

  • jim

    nj does not allow plea bargains on dui, nj does not allow expungment of dui.

    what now?