The subject of DWI and DUI is surrounded by common myths which are corrected here with scientific information and evidence.

Research using experienced law enforcement officers has found that odor strength estimates are unrelated to blood alcohol concentration (BAC), which ranged in the experiment from zero to .13 (almost twice the legal limit for driving). The estimates made by the officers were no more accurate than random guesses. The researchers concluded that estimates of alcohol on the breath are unreliable.2

Even in the absence of any of these common problems and under ideal conditions, alcohol breath testers simply lack precision. Law professor and attorney Lawrence Taylor explains that “Scientists universally recognize an inherent error in breath analysis, generally of plus or minus .01%.” In addition “This has been acknowledged by courts across the country (see, for example, People v. Campos, 138 Cal. Rptr. 366 (California); Haynes v. Department of Public Safety, 865 P.2d 753 (Alaska); State v. Boehmer, 613 P.2d 916 (Hawaii), recognizing an even larger .0165% inherent error).6

This means that under ideal conditions, which is a highly unlikely situation, a BAC reading of .08 reflects an actual BAC of anywhere from .07 to .09 or even .065 to .095. That’s a margin of error of 20 to 30 percent.

Would this be considered a reasonable margin of error for an accountant, airline pilot, or bank teller? Is this a reasonable margin of error in court, where guilt should be proved beyond a reasonable doubt?

"In all criminal prosecutions, the accused shall enjoy the right to a speedy and public trial, by an impartial jury of the State and district wherein the crime shall have been committed..."

The Sixth Amendment provides no exceptions to this fundamental right to a trial by jury in all criminal cases.

Although you may have overwhelming evidence of many types and from many sources that prove your BAC reading is erroneous and that you are innocent of DWI, many states will deny you a jury trial.7

"By far, the most overlooked error in breath testing for alcohol is the pattern of breathing.... The concentration of alcohol changes considerably during the breath...The first part of the breath, after discarding the dead space, has an alcohol concentration much lower than the equivalent BAC. Whereas, the last part of the breath has an alcohol concentration that is much higher than the equivalent BAC. The last part of the breath can be over 50% above the alcohol level....Thus, a breath tester reading of 0.14% taken from the last part of the breath may indicate that the blood level is only 0.09%."8

Professor Taylor explains that

“Many police officers know this. They also know that if the machine contradicts their judgment that the person they arrested is intoxicated, they won’t look good. So when they tell the arrestee to blow into the machine’s mouthpiece, they’ll yell at him, "Keep breathing! Breathe harder! Harder!" As Professor Hlastala has found, this ensures that the breath captured by the machine will be from the bottom of the lungs, near the alveolar sacs, which will be richest in alcohol. With the higher alcohol concentration, the machine will give a higher -- but inaccurate - - reading.”9

In reality, alcohol breath testers detect any chemical compounds that contain the methyl group in its molecular structure. Unfortunately, there are thousands of such compounds. Many occur naturally in the human breath or are picked up from disease; inhaling fumes from gasoline, glue, paint, paint remover, “new car smell,” celluloid, cleaning fluids, etc.10

Breath testers also assume as constants certain ratios within the human body that actually vary widely from person to person and within the same person over time. For example, many breath-testing machines assume a 2,100-to-1 ratio in converting alcohol in the breath to estimates of alcohol in the blood. However, this ratio varies from 1,900 to 2,400 among people and also within a person over time. This variation will lead to false BAC readings. Some breath analysis machines assume a hematocrit (cell volume of blood) of 47%. However, hematocrit values range from 42 to 52% in men and from 37 to 47% in women. A person with a lower hematocrit will have a falsely high BAC reading. These machines appear to discriminate against female suspects.

• www.snopes2.com. There is no scientific reason to believe that sucking on copper would have any effect on the results of alcohol breath tester BAC results and no evidence has been published in any scientific publication indicating that it does.
• Moscowitz, H., Burns, M. & Ferguson, S. Police officers’ detection of breath odors from alcohol ingestion, Accident Analysis and Prevention, 1999 (May), 31(3), 175 180.
• Lindiger, W., Taucher, J., Jordan, A., and Vogel, W. Endogenous production of methanol after the consumption of fruit. Alcoholism: Clinical and Experimental Research, 1997, 21, 939-943; Phillips, M., Greenberg, J., and Martinez V., Ostrovsky, Y. M. Endogenous ethanol -- its metabolic, behavioral and biomedical significance. Alcohol, 1986, 3, 239-247; Mullholland and Townsend, Bladder Beer - A New Clinical Observation, 95 Transactions of the American Clinical Climatological Association, 1983, 95, 34; Jones et al., Determination of endogenous ethanol in blood and breath by gas chromatography, Pharmacology, Biochemistry and Behavior, 1983, 18, 267.
• Brick. Diabetes, breath acetone and Breathalyzer accuracy: a case study, Alcohol, Drugs and Driving 1993, 9(1). See Taylor, Lawrence. Diabetes and the Counterfeit DUI (http://www.duiblog.com/2004/10/18).
• Cole, S. & Nowaczyk, R.H. Field sobriety tests: are they designed for failure?, Journal of Perceptual and Motor Skills, 1994, 79, 99-103.
• Taylor, Lawrence. Close Enough for Government Work. (www.duiblog.com/2004/11/30)
• Taylor, Lawrence. DUI and the Disappearing Right to a Jury Trial (www.duiblog.com/2004/10/31#a25)
• Hlastula, M. Physiological errors associated with alcohol breath tests. The Champion, 1985, 9(6).
• Taylor, Lawrence. How to Fool the Breathalyzer. (www.duiblog.com/2004/11/27)
• Jauhonen, P., et al. Origin of breath acetaldehyde during ethanol oxidation: Effect of long-term cigarette smoking. Journal of Laboratory Clinical Medicine, 1982, 100(6), 908-916.