The Top 20 Myths

of Breath, Blood and Urine Tests You need to know to defend when DUI/DWI convicted

The top 20 myths of breath, blood and urine tests used in DUI defense

When the experts disagree, who are we to believe? As Learned Hand observed:

The whole object of the expert is to tell the jury, not facts . . . but general truths derived from his specialized experience. But how can the jury judge between two statements each founded upon an experience confessedly foreign in kind to their own? It is just because they are incompetent for such a task that the expert is necessary at all.
Learned Hand, Historical and Practical Considerations Regarding Expert Testimony, 15 Harv. L. Rev. 40, 53 (1901).

Defending against DUI / DWI

This article explores disagreements among the experts — the myths commonly employed by courts, police, and prosecutors, and often accepted by defense lawyers in drunk driving cases, and the published scientific articles debunking those myths. In some cases, there is honest debate about the validity of the state’s methods and theories. In other cases, the state’s experts’ conclusions are translated improperly by police and prosecutors, to the detriment of defendants. The point of this article is not to comprehensively discuss every point of view, but to quote some of the published scientific articles that challenge the status quo.

Most of these articles cannot be found in a law library or on Westlaw or Lexis. One major resource for exploring scientific literature related to drunk driving is While this is an excellent resource for reading abstracts of the articles, unless one subscribes to the relevant scientific journals, it is often necessary to do research “the old fashioned way” and copy these articles at a medical library. There are also innumerable scientific texts covering our subject, many of which were excellent resources in writing this article. Among them, Medical-Legal Aspects of Alcohol, (James G. Garriott ed., 4th ed. 2004), contains articles by the leading experts in the field, including Dr. A.W. Jones and Dr. Kurt Dubowski. A legal treatise that discusses some of the scientific literature in depth is Edward F. Fitzgerald, Intoxication Test Evidence (2nd. ed.).1

Effective DUI / DWI Defense

Most of the articles discussed here have been “peer reviewed.” Peer review “increases the likelihood that substantive flaws in methodology will be detected.” Daubert v. Merrell Dow Pharms., Inc., 509 U.S. 579, 593-94 (1993). It refers to a process of editing. Kenneth K. Altman, The Myth of “Passing Peer Review,” in Ethics and Policy in Scientific Publication 257, 262 (Council of Biology Editors, Inc. 1990). Scientific publication is not immune to falsification of data, plagiarism, conflict of interest, and politics. Id. Most commentators agree that the quality of published scientific articles is enhanced by peer review. However, how much is anyone’s guess and differs from journal to journal.

Certainly the author’s background and past and present affiliations may be relevant to an evaluation of him or her. Many of the published researchers in the field of forensic toxicology related to alcohol testing are presently or were formerly employed by, or affiliated with, state alcohol testing programs. While this does not necessarily create a conflict of interest, it may indicate a bias that is relevant to an assessment of an article’s credibility or an author’s testimony in court.

Finally, it is important to recognize that many scientific articles rely on the language of statistics in reaching their conclusions. Statistical concepts are often not well translated into legal concepts, like the concept of proof beyond a reasonable doubt. This allows the state to employ a mathematical slight of hand, using a preponderance standard to secure admission of test results and then arguing that they have satisfied the higher standard of proof beyond a reasonable doubt.

It is with these considerations in mind that we turn now to the top 20 myths in breath, blood, and urine testing.

Next article: Myth #1: Breath Means Alveolar Air

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