DUI BLOG

In my previous post, I discussed the problem of mouth alcohol – that is, falsely high breathalyzer readings caused by alcohol samples coming from the mouth rather than from the lungs.  And the response from some of our more sophisticated readers (law enforcement and/or lawyers?) has been predictable:  What about mouth alcohol detectors?

Some breath machines have what is called a slope detector, commonly referred to as a “mouth alcohol detector”.  This is an electronic circuit designed to detect the presence of mouth alcohol as the breath is being captured by the machine.  It does this by detecting any pronounced negative slope in the alcohol intake curve, since alcohol content from the mouth or throat will decline more rapidly than alcohol from the lungs.  In theory, the presence of mouth alcohol will cause the test to abort.

Unfortunately, these “detectors” are simply unreliable, due primarily to a design flaw.  Rather than try to explain the technical defects, I will let Dr. Michael Hlastala, Professor of Physiology, Biophysics and Medicine at the University of Washington School of Medicine, explain:

The slope detector is problematic for all breath instruments and has been misrepresented by the manufacturers. 

When a subject with alcohol in the blood, with no extra alcohol in the breath, exhales, the breath alcohol continues to increase during exhalation.  It does not reach a “plateau” until the end of airflow.  It continues to rise, giving a positive slope.  If you swish a little alcohol in the mouth (and have no alcohol in the blood), wait awhile and exhale, the breath alcohol will rise until a peak is reached about 1/3 of the way into the exhalation, and then decline gradually.  It is the declining breath alcohol (negative slope) that triggers the slope detector to register the breath as having mouth alcohol.

If the subject has alcohol in the blood as well as the mouth, then the normal rising breath alcohol curve will add to the declining mouth alcohol curve to produce what is often a level curve.  Thus, the slope detector is unable to detect the presence of mouth alcohol when some is present in the mouth, yet breath alcohol concentration will be higher than it should be.  The slope detector cannot detect false mouth alcohol under this circumstance.

To make matters worse, the slope/mouth alcohol detectors are never calibrated by the police, as this has to be done at the factory.  The only thing police technicians do is simply rinse their mouth with alcohol and then breath into the machine: if the detector is triggered, it is assumed to be working.  But as Professor Hlastala has observed:

Whenever the slope detector is checked, it is done with alcohol in the mouth, but not in the blood.  Therefore, the slope detector serves no purpose and mouth alcohol frequently affects the breath alcohol reading.

Bottom line:  Despite the claims of manufacturers anxious to sell their machines, these detectors are unreliable and mouth alcohol remains a serious problem in breath alcohol analysis.

One of the most common causes of falsely high breathalyzer readings is the existence of mouth alcohol.

The breathalyzer’s internal computer is making a major assumption when it captures a breath sample and then analyzes it for blood alcohol concentration (BAC): It assumes that the alcohol in the breath sample came from alveolar air — that is, air exhaled from deep within the lungs. Since we are trying to measure how much alcohol is in the blood, rather than in the breath, the computer applies a formula to translate the results. This formula is based upon the average ratio of alcohol in the breath to alcohol in the blood. This so-called partition ratio is 1 to 2100 — that is, in the average person there will be 2100 units of alcohol in the blood for every unit measured by the breathalyzer in the breath. Put simply, the machine’s computer multiplies the amount of alcohol detected in the suspect’s breath sample by 2100 and reports that as the blood alcohol level.

But what if the alcohol in the sample is not from the lungs?

Too bad: the machine doesn’t know any better. If there is even a miniscule amount of alcohol in the DUI suspect’s mouth or throat, it will be tremendously magnified by the breathalyzer and it will report a much higher BAC than the true one.

Alcohol can be found in the mouth for a number of reasons. The most obvious is that the individual has recently consumed some alcohol; it usually takes 15-20 minutes for the alcohol to dissipate through the rinsing action of saliva. Or he/she may have recently used mouthwash or breath freshener (most contain fairly high levels of alcohol) — possibly to disguise the smell of alcohol when being pulled over by police. See my earlier post, Breath Fresheners and Breathalyzers.

The most common source of mouth alcohol is from eructation (burping or belching). This causes the liquids and/or gases from the stomach — including alcohol if it is there — to rise up into the soft tissue of the esophegus and mouth, where it will stay until it has dissipated. For this reason, police officers are required to keep a DUI suspect under observation for at least 15 minutes prior to administering a breath (in reality, however, many if not most officers are unwilling to stand around watching a suspect for a quarter of an hour).

Acid reflux can greatly exacerbate this problem. As was discussed in a previous post, GERD, Acid Reflux and False Breathlayzer Results, the stomach is normally separated from the throat by a valve. When this valve becomes herniated, there is nothing to stop the liquid contents in the stomach from rising and permeating the esophegus and mouth. The contents — including any alcohol — is then later breathed into the breathalyzer. Since it has not yet been absorbed through the stomach wall and into the blood and eventually into the lungs, this alcohol should not be read as breath from the lungs and multiplied by 2100. Of course, the breathalyzer doesn’t know this. See the article by Kechagias, et al., “Reliability of Breath-Alcohol Analysis in Individuals with Gastroesophogeal Reflux Disease”, 44(4) Journal of Forensic Sciences 814 (1999).

The mouth alcohol problem can also be created in other ways. Dentures, for example, will trap alcohol for much longer than 15-20 minutes. Periodental disease can also create pockets in the gums which will contain the alcohol for longer periods. And so on…. As the American Medical Association’s Committee on Medical Problems concluded in its Manual for Chemical Tests for Intoxication (1959):

True reactions with alcohol in expired breath from sources other than the alveolar air (eructation, regurgitation, vomiting) will, of course, vitiate the breath alcohol results.

As I have said in earlier posts, law enforcement investigation techniques depend largely upon the fictitious premise that all humans are physiologically identical (see “Convicting the Average DUI Suspect”). Without that presumption, field sobriety and breath alcohol tests would not be possible. I have previously discussed many examples of physiological differences — from person to person and within one person from moment to moment — which will directly alter breath or blood alcohol testing (see, for example, “Diabetes and the Counterfeit DUI”, “GERD, Acid Reflux and False Breathalyzer Results” and “The Effect of Anemia on Breath Tests”).

Yet another example of variability is body temperature. Put simply, an individual’s body temperature will have a direct effect on the results of a breath test. The effects of changes in body temeprature from the norm of 98.6 degrees on breath testing has been discussed in an article entitled “Body Temperature and the Breathalyzer Boobytrap”, 721 Michigan Bar Journal (September 1982). If because of illness, for example, the body temperature is elevated by only 1 degree Centrigrade (1.8 degrees Fahrenheit), the 1:2100 breath-to-blood partition ratio will be affected so as to produce a 7 percent higher test result. Higher body temperatures will, of course, result in greater errors.

Dr. Michael Hlastala, Professor of Physiology, Biophysics and Medicine at the University of Washington, confirms this effect. In an article entitled “Physiological Errors Associated with Alcohol Breath Testing”, 9(6) The Champion 18 (1985), he comments that even the average body temperature of a normal, healthy person “may vary by as much as 1 degree Centigrade above or below the normal mean value of 37 degrees Centigrade — or 1.8 degrees from the mean value of 98.6 degrees Fahrenheit”.

Not only can the normal mean body temperature of an individual vary from that of other persons, but the “temperature of any individual may vary from time to time during the day by as much as 1 degree Centigrade”. Result? The partition ratio for alcohol in blood is altered — meaning, according to Professor Hlastala, a 6.3 percent error for every 1 degree Centigrade increase or decrease from the presumed normal body temperature. Yet another example of how breathalyzers are not actually testing you, but rather an “average” person who does not exist.

Ok, this story isn’t exactly about drunk driving, but it sure reflects the increasingly arrogant attitude of prosecutors we encounter in DUI cases here in Southern California: 

LOS ANGELES (March 24) AP – Jurors who acquitted actor Robert Blake of murder – and were later called “incredibly stupid'’ by District Attorney Steve Cooley – want an apology.

“I’m just disgusted,'’ Blake jury foreman Thomas Nicholson said Thursday. “It appears to me he has no faith in the jury selection. After all, it was his people who helped choose us.'’

Loyola University law professor Laurie Levenson called Cooley’s comment a
major lapse in judgment – and “much more of an embarrassment for him than the jurors'’….. On Thursday night, Cooley stood by his comments.

But this is the real mind-blower:

“Bottom line it was the wrong verdict,'’ he said. “Sometimes jurors should be held accountable for their mistakes.'’

I hate to think what Cooley has in mind for making jurors “accountable”, but I’m pretty sure ”mistakes” means aquittals…..

The previous two posts on the physiological sources of inaccuracy in breath alcohol analysis have apparently caused considerable interest…and a number of queries. Let me be clear: Simpson is far from alone in his conclusions. Those involved in forensic alcohol analysis will generally recognize that the most recognized authorities in the field include Dubowski, Jones, Simpson and Hlastala. In the posts I quoted supporting conclusions from Dubowski and Hlastala; Jones has expressed somewhat similar views. To quote further from Professor Dubowski on physiological sources of error (as opposed to operator error or defects in the design or function of the machine itself — of which there are many):

First, not all blood and breath alcohol curves follow the Widmark pattern, nor is the elimination phase linear. Second, alcohol absorption is not always complete within 60 to 90 minutes as often claimed. Third, the peak alcohol concentration cannot be validly predicted or established in an individual instance without frequent and timely measurement of alcohol concentrations. Fourth, it is not possible to establish whether an individual is in the absorption or elimination phase, or to establish the mean overall rate of alcohol elimination from the blood or breath, from the results of two consecutive blood or breath alcohol measurements, however timed. Fifth, significantly large short-term fluctuations occur in some subjects and result in marked positive and negative departures from the alcohol concentration trend line. Sixth, short-term marked oscillation of the blood or breath alcohol concentration can occur at various points on the curve, resulting in repeated excursions of the alcohol concentration above and below a given concetration within a few minutes or for hours. Finally, no forensically valid forward or extrapolation of blood or breath alcohol concentrations is ordinarily possible in a given subject and occasion solely on the basis of time and individual analysis results.

Dubowski, "Absorption, Distribution and Elimination of Alcohol", 10 Journal of Studies on Alcohol, Suppl. 98 (1985). And those are just some of the physiological problems when trying to measure blood alcohol. We also have to consider: possible errors by the cop in operating the machine; malfunctions in the machine; design defects (there are many: see, for example, "Breathalyzers — and Why They Don’t Work" and "Why Breathalyzers Don’t Measure Alcohol"); maintenance and repair issues; calibration errors; and so on…. But, as they say in DUI law enforcement, "close enough for government work".

I’ve received considerable response to yesterday’s post, "Breathalyzer Inaccuracy: Testing During the Absorptive State", including questions concerning the accuracy of breath machines after the absorptive state. Even in the post-absorptive state — that is, when the body has reached a state of equilibrium, or uniform distribution of alcohol — there are numerous sources of error attributable entirely to physiological factors. Simpson’s research has found that breath tests are inherently unreliable, indicating uncertainty levels of 15 to 27 percent. In an article written shortly before the one cited yesterday, he noted:

Over 90% of this uncertainty is due to biological variables of the subject, and at least 23% of subjects will have their actual blood alcohol concentration overestimated. Manufacturers’ specifications for the accuracy and precision of these instruments are inconsistent with the experimental values reported in the literature and I recommend that an appropriate amount of uncertainty be reflected in the results from these breath analyzers, especially when they are used for law-enforcement purposes.

Simpson, "Accuracy and Precision of Breath Alcohol Measurements for Subjects in the Absorptive State", 33(2) Clinical Chemistry 261 (1987). Another noted expert, Professor Michael Hlastala, Professor of Physiology, Biophysics and Medicine at the University of Washington’s Medical School, concludes:

Breath testing, as currently used, is a very inaccurate method for measuring BAC. Even if the breath testing instrument is working perfectly, physiological variables prevent any reasonable accuracy…

Hlastala, "Physiological Errors Associated with Alcohol Breath Testing", 9(6) The Champion 19 (1985).

In previous posts, I have 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 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 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."

Some time ago I talked about "the future of DUI", trying to identify trends of the past and project into the future on such issues as probable laws, blood alcohol evidence, constititional rights, the growing federal presence — and the movement toward a "New Prohibition". Although I predicted that MADD's agenda of resurrecting that failed experiment would eventually fail, I was thinking of a frontal attack — that is, an amendment to the Constitution as happened before. I recently received the following insightful comments concerning that post from a good friend and one of the top half-dozen DUI attorneys in the country today, Troy McKinney of Houston:

If there is one thing that our country's politicians have learned it is that is far easier to make small incremental changes through economically motivated laws than through unfunded mandates or constitutional amendments. Over time, these small changes significantly change the landscape.

Thus, I see there being a New Prohibition, but only a statutory one that originates at the federal level. I think it is likely that the feds will impose new, increasingly onerous requirements as conditions for federal dollars — to the extent that we will have a federally imposed statutory prohibition on alcohol.

I think the future of this federal prohibition will include, within the next 20 years, all new cars being manditorily equipped with ignition interlock devices — and ones much more sophisticated and onerous than those used today — perhaps even to the extent that a positive blow will itself be a crime that is remotely reported to law enforcement at the time of the positive blow along with a continuous GPS signal for location purposes.

I can envision passive alcohol sensors in vehicles that continually sample the ambient air. Once an ignition interlock company merges with an OnStar, the stage will be set. With 16-18 million new cars a year cranked out in this country, it offers these companies a HUGE market opportunity.

I doubt that I am the first to envision the long term possibilities and it would not surprise me if some of these companies already had plans like this on the drawing board. These companies are already very active on the legislative and regulatory front and it will only increase, dramatically so in my view.

A true zero tolerance drinking and driving society will markedly affect the sale of any alcoholic beverage as well as the sale of packaged alcohol for anything but personal consumption in one's own home. This will in turn lead to an effective, although not absolute, Prohibition.

Orwell had it mostly right, he was just a bit early in his predictions.

As with so many glacial shifts in history, we are seeing no revolution, no sudden dismemberment of the Constitution, but rather something like the old Chinese torture, "the death of a thousand cuts".

Experienced traffic patrol officers are familiar with a phenomenon which is sometimes referred to as "black-and-white fever". That phenomenon is simply the normal reaction of most drivers to being followed by a marked police car (painted, in many jurisdictions, black and white).

As soon as the motorist becomes aware that a police car is following him, he becomes understandably apprehensive’and focuses his attention increasingly on the rear view mirror. As the officer continues to follow, the driver becomes tense, worried, and his concentration on driving is broken: He keeps his eyes more on the mirror and less on the road ahead. Each time the driver brings his eyes back to the road, he finds that he has drifted and must correct the course of the car back to the center of the lane.

The result: weaving’and, possibly, erratic movements such as sudden increases or decreases in speed (tension can cause the foot to depress the accelerator). And, of course, these are the most commonly encountered symptoms of a drunk driver on the highway. In other words, it is the very presence of the officer which tends to create the probable cause for suspecting a DUI. And after the officer pulls the driver over, he gets out and approaches the car with the very human preconception that the driver is probably intoxicated.

And, as we know from psychological studies, we tend to see what we expect to see: normally veined eyes appear "bloodshot", normally but stressed speech sounds "slurred", normal pink complexions appear "flushed", etc. These observations are quickly followed by the notoriously subjective field sobriety tests, difficult to perform under the best of conditions. Followed in turn by an arrest for DUI.

Individuals convicted of DUI are often required to have an ignition interlock device installed (at their expense) in their cars. These notoriously inaccurate and unreliable gizmos are designed to prevent the ignition from working until after the driver has breathed into a mouthpiece and registered alcohol-free (although it takes little imagination to realize that a drunk driver can start the car by simply having his passenger breathe into the device).

This latest weapon in the "war on drunk driving" has been adopted in many states with the strong lobbying of MADD — and of manufacturers who make a huge profit on the devices. Consider a story in today's (March 16, 2005) Arizona Republic:

First-time DUI offenders could agree to equip their vehicles with an ignition interlock device to prevent drunken driving rather than face suspended driver's licenses under a bill that breezed through the Senate on Tuesday….. Alberto Gutier, a former highway safety director lobbying for the Arizona Interlock Distributors Association, said increased sales isn't the bill's purpose. "It's not about expanding the market, it's about preventing drunk driving," Gutier said.

The bottom line, of course, is: Do IIDs prevent drunk driving? Do they make our streets safer? MADD claims that their "research" shows they do:

Interlocks have been shown to be effective in Maryland, Alberta, California and elsewhere with results ranging from 50 to 90 percent reductions in subsequent offenses by those offenders who were assigned interlock devices, compared with those who were not….. While interlocks are not the only solution, as offenders tend to go back to their old ways once the device is off of the vehicle, they certainly keep the roads safer while these devices are in place.

Effective in California? Keep the roads safer? The California Department of Motor Vehicles has just released a study entitled An Evaluation of the Effectiveness of Ignition Interlock in California: Report to the Legislature of the State of California. Among their conclusions:

The expected effect that an IID order/restriction issued by the court would result in a lower rate of subsequent DUI convictions was not observed. (p. 7) The risk of a subsequent crash was higher for drivers installing an IID, compared to drivers not installing a device; drivers installing an IID had a risk of a subsequent crash that was 84% higher than drivers not installing an IID. (p. 10) The results of this outcome study clearly show that IIDs are not effective in reducing DUI convictions or incidents for first DUI offenders … Because there is no evidence that interlocks are an effective traffic safety measure for first DUI offenders, the use of the devices should not be emphasized. (p. 22)

Facts notwithstanding, MADD continues its campaign for ignition interlock devices, as evidenced by a Tuesday (March 15, 2005) news article in the Tallahassee Democrat:

Mothers Against Drunk Driving held its annual legislative lobbying day, urging Florida lawmakers to lower the blood-alcohol threshold that triggers "double-drunk" penalties and calling for easier authorization of ignition-interlock devices for repeat offenders….