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Residual Mouth Alcohol, Slope Detectors and the 20 Minute Observation

Dayton DUI Attorney Charles Rowland > DUI Law  > DUI Process  > Residual Mouth Alcohol, Slope Detectors and the 20 Minute Observation

Residual Mouth Alcohol, Slope Detectors and the 20 Minute Observation

Someone using a breathalyzer

One of the most prevalent causes of error in breath-alcohol analysis is the presence of alcohol in the mouth.  This residual mouth alcohol (hereinafter R.M.A.) contaminates the expired breath captured by the machine and elevates the test results radically.  The BAC Datamaster’s computer is programmed to assume that a breath test reading is 100% deep-lung (alveolar) air.  This captured “deep-lung” air is then multiplied by 2100 pursuant to the accepted and scientifically defensible partition ratio.[1] Using these built-in assumptions it is evident that a very small amount of undigested (or trapped) alcohol can have a disproportionate impact on the reading.

At DUI seminars, OVI defense attorneys will often trot out a 55 gallon drum and an eye dropper.  The 55 gallon drum represents roughly the same capacity as a 210 liter sample of air (the volume used in the machine’s breath analysis) and the eye dropper is loaded with just a drop of liquid.  The infinitesimal amount of liquid is used to demonstrate to the jury how even just a drop in the bucket (of undigested R.M.A.) can lead to a falsely elevated test.


Mouth alcohol contamination is not a myth made up by OVI defense attorneys.  The manufacturers of the BAC Datamaster addresses the importance residual mouth alcohol in their own materials.  “The importance of observing the initial waiting period of 15[2] minutes, minimum, cannot be overstressed.  Around it hinges all the statements of scientific certainty regarding the validity of the breath test reading without any possible contribution from mouth alcohol.” Fusco & Radomski, Basic Science of Evidential Breath Alcohol Testing, p. 14. (emphasis added)  The phenomenon of R.M.A. has been recognized by the American Medical Association’s Committee on Medical Problems, which stated in its Manual for Chemical Tests for Intoxication (1959): “True reactions with alcohol in expired breath from sources other than alveolar air (i.e.. alcohol trapped in dentures) will, of course, vitiate the breath alcohol results…”[3] And see Caddy, Sobell and Sobell, “Alcohol Breath Tests: Criterion Times for Avoiding Contamination by ‘Mouth Alcohol,’”[4] in which the authors conclude that when a subject is given ethyl alcohol in concentrations ranging from 4 percent to over 95 percent, the time for total dissipation of the mouth alcohol ranged from 10 to 19 minutes.

Science has also focused on dentures causing unduly high readings.  A study conducted by the Colorado Department of Health  placed a wafer style dental adhesive (Sea-Bond) into a subject’s mouth and then had him drink approximately 8 milliliters of a 50 percent ethyl alcohol and water solution.  He was then tested on infra-red breath testing devises every five minutes.  He had immediate readings of .480 percent – indicating a BAC level that would cause death in most.  The .480 reading was repeated at the 5 and 10 minute tests; the BAC level dropped to .425 percent after 15 minutes and to .314 percent after 20 minutes. The subject was still registering .112 percent after 35 minutes, indicating a BAC level in excess of Ohio’s per se limits despite having actually consumed an insignificant amount of alcohol.  As a result of this study, Colorado’s Department of Health issued an advisory to the State’s breath test operators that dental adhesives were to be considered a foreign object and that dentures were to be removed prior to any evidentiary testing.[5] The results of this study eerily mirror the tests results now before the court.


Wisconsin conducted a study which is frequently cited by the prosecution-oriented.[6] It tested twenty-five subjects and focused on whether dentures affect mouth alcohol.  The test concluded that “dentures do not significantly affect mouth alcohol retention time .”  However, the test was flawed for purposes sub judice.  Only 25 subjects were used in this study; the study focused not on trapped or ambient alcohol but on dissipation; the author of the study went on to become the leading defense expert in the western United States (MacMurray); and the authors of this study and Fusco and Radomski warn in their literature, “Slope detection is not a substitute for procedural countermeasures.” See Fusco and Radomski, Id. At 16.  The conclusions that can be drawn from the best prosecution-oriented study are thus:  Look for and remove dentures if you can!

It is also important to note that the slope detector on the machine can be “fooled” by the consistent presence of mouth alcohol.  In order to “trip” the slope detector must register a “spike.”  Here, the denture’s trapped alcohol would allow for a uniform reading.  The machine will not detect an anomaly and will not detect a negative slope.  In fairness to the machine, no negative slope would be present, just an anomalous reading.  Again, we have scientific studies to back up this assertion.  In “Breath-Alcohol Concentration May Not Always Reflect the Concentration of Alcohol in Blood” 18 J. Analytical Toxicology 225 (July/Aug 1994), a 37 year-old man consistently recorded levels twice the legal limit, but had an actual blood-alcohol concentration below the legal limit.  Although the researchers could give no explanation, they did note the existence of extensive dental work, including three bridges.  A forensic odontologist expressed the view that a reservoir of alcohol might be retained within the spaces occupied by these bridges and that this might be the possible explanation for the excessively high breath-alcohol readings observed.



When applying the science to the law, the Court can look to recent law as set forth below which would grant the court the power to invalidate the test.  However, the State’s best argument is to avoid application of the science by the court and have the issue go before a jury.


In State v. Baldridge 2001-Ohio-7029, 2001 WL 1673756 (Ohio Ct. App. 5th Dist. Ashland Co. 2001) as cited in Painter, Ohio Driving Under the Influence Law (2007 Ed.), p 121, the Court held that whether a subject has something in his mouth is a bright-line rule to which the substantial compliance standard is inapplicable. (emphasis added). Within the context of Ohio Adm. Code 3701-53-02, the term “oral intake” for purposes of submitting to a chemical test, means that material must be orally ingested in such a manner that it would be digested and pass into the blood stream, or received into the respitory system and interact with alveolar air so as to have an effect on the breath test result. State v. Birth (1987) , 41 Ohio App. 3d 113.  The science cited above and a clear reading of both the case law and Ohio Adm .Code 3701-53-02 would result in the test being excluded.


It is within the trial court’s discretion to weigh evidence and determine credibility whether the required observation period was met. State v. Edens, 1987 WL 15054 (Ohio Ct. App. 11th Dist. Portage County 1987); State v. Williamson, 1985 WL 6754 (Ohio Ct. App. 1st Dist. Hamilton County 1985); State v. Trill, 66 Ohio App.3d 622, 585 N.E.2d 914 (11th Dist. Trumbull County 1991); State v. Gregory, 1999 WL 756440 (Ohio Ct. App. 7th Dist. Columbiana County 1999).

The State’s best argument for introduction of the test is that it substantially complied with the testing procedures set forth by the Ohio Department of Health.  The State can effectively side-step the science, cited above, and argue that the dentures do not constitute oral intake because they were already in the Defendant’s mouth during the twenty minute observation period.  That is the argument made in State v. Arledge, 4th Dist Ct. App. Hocking County 91-WL 5059.  The argument therein stated that because the officer followed the ODH regulations and no “oral intake” occurred during the twenty minute observation period, substantial compliance required the issue to go to the jury.

In effect the Arledge court interpreted Ohio Adm. Code 3701-53-02 to preclude only oral intake. Within the context of Ohio Adm. Code 3701-53-02, the term “oral intake” for purposes of submitting to a chemical test, means that material must be orally ingested in such a manner that it would be digested and pass into the blood stream, or received into the respitory system and interact with alveolar air so as to have an effect on the breath test result. (emphasis added) State v. Birth (1987) , 41 Ohio App. 3d 113.

The mouth and throat are part of the respitory system.   The presence of trapped alcohol in the dentures would be received into the respitory system and would have an effect on the results.  Such an interpretation would bring the two cases in compliance with the later case law (State v. Baldridge) cited above.  In dicta, even the Arledge court suggests that the best course of action would be to remove the dentures.

A further factor which is only addressed in the footnotes of Arledge is the courts “gatekeeper” function.  The trial court has broad discretion in admitting and excluding evidence based on scientific processes. State v. Bresson (1990), 51 Ohio St.3d 123, 129.  Further, Evid.R. 403 grants the court power to exclude “junk” science via a motion in limine.  From a purely procedural aspect the entire Arledge decision is rendered moot by a proper request in limine.

In State v. Siegel, 138 Oiho App.3d 562, 2000-Ohio-1747, 741 N.E.2d 938 (3d. Dist. Logan County 2000), the Court ruled that the oral intake of any material, including water, renders the test as not substantially compliant with ODH regulations.  In State v. Dixon, 2002-Ohio-6174, 2002 WL 31521434 (Ohio Ct. App. 5th App. Dist. Stark County 2002), the ingestion of breath mints during the twenty minute observation period resulted in a finding that the State had not substantially complied.


The science supports exclusion of the test.  R.M.A. is likely and that the resulting test is compromised..  If the court wishes to venture into the realm of “whether or not the State substantially complied with ODH regulations,” I cite the critique of such an approach by Judge Painter who states:

In legal as well as scientific matter, rigid lines often create considerable disputes even among experts.  Absent strict adherence to the established standards, any testing regulation may be open to further expansion of its parameters justified by a substantial compliance approach.  For example, does an instrument check or calibration of a breath-testing device once every eight, rather than seven, days substantially comply with O.A.C.  3701-53-04(A)?  Under the foregoing circumstances would a defendant’s breath test result be admissible unless prejudice was demonstrated?  The Ohio Supreme Court recognized this problem in State v. Burnside, 100 Ohio St.3d 152, 2003-Ohio-5372, 797 N.E.2d 71 (2003).  Citing this book, that court determined that it should limit Plummer to “excusing errors that are clearly de minimus.”  The court emphasized that the criterion for admissibility under RC 4511.19 was compliance with the regulations, and not judicial determination of the reliability of the tests.[7]

“It is better that ten guilty go free than that one innocent be punished.”

[1] The machine observes a theoretical “constant” ratio between the concentration of alcohol in the blood and the concentration in the deep lung air.  The average ratio among human beings is generally accepted as being 1:2100, that is, the same weight of alcohol will be in one cubic centimeter of deep-lung (pulmonary lung) air as in 2.1 liters of deep lung breath.  This is, of course, only an average an studies have concluded that the ratio, in fact varies widely. See S. Tsukamoto, et al., An Experimental Study on the Ethanol Ratio of Breath to Blood, 37 Japan J. Legal Med. 823 (1983).

[2] The State of Ohio, through its Department of Health has followed the majority of states in lengthening the mandatory observation period to twenty (20) minutes.

[3] Cited originally in Taylor, Drunk Driving Defense (6th Ed., 2006) pp. 424

[4] 10(6) Behavior Research Methods & Instrumentation 814-18 (1978).

[5] The resulting actions of the study upon Colorado’s Department of Health are set forth at Taylor, Drunk Driving Defense, (6th Ed., 2006) p. 425.

[6] Harding, P. MacMurray M. et al. “THE EFFECT OF DENTURES AND DENTURE ADHESIVES ON MOUTH ALCOHOL RETENTION” Journal of Forensic Sciences, July 1992.

[7] Painter, Ohio Driving Under the Influence Law, (2007 Ed.) pp. 111.

Charles Rowland


Charles M. Rowland II has been representing the accused drunk driver for over 20 years. Contact him at (937) 318-1384 if you find yourself facing a DUI (now called OVI) charge.

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