DUI Defense: New Article Supports National Push to Make PBT Results Admissible as Evidence - But Not So Fast - April, 2015

In Michigan, probable cause to make an arrest may be established in whole or in part based upon the result of a preliminary breath test (PBT). The result of this analysis is admissible (along with other competent evidence) in a criminal prosecution for a drunk driving offense to assist the court in determining a challenge to the validity of an arrest.1

However, the enforcement and prosecution of laws applicable to intoxicated driving vary considerably among the states.  In some states PBTs are rarely employed as part of a DUI investigation, while in others, such as Michigan, they are used for nearly every arrest.  In those states where PBTs are regularly used, there is disparity as to whether or not the results obtained from a PBT device are admissible for evidentiary purposes—either at pretrial when contesting an arrest, or at trial to support intoxication.

A newly published technical note in the Journal for Forensic Sciences, entitled “The Accuracy of Handheld Pre-Arrest Breath Test Instruments as a Predictor of the Evidential Breath Alcohol Test Results”2, suggests that a national effort should be made to increase, if not mandate, the admissibly of PBTs for evidentiary purposes in intoxicated driving cases.  As indicated in the article “the purpose here is to evaluate the evidentiary value of the PBT instrument and assess its predictive value,” which “would provide support in evidential [Frye3] or [Daubert4] hearings attempting to obtain admissibility of their results in DUI litigation.”  Furthermore,

While the primary purpose here is not to suggest that the PBT results will be evidential without further quality control considerations, findings such as those presented here may allow the PBT results to be admissible in court in support of the drunk driving offense under certain circumstances.  Where the evidential test is not available, the PBT results provide evidence that should be considered by the court.  A strong case can be made for the admissibility of the PBT results employing such methods and findings as presented here along with other considerations.

In compiling the data for the study, the authors looked at and compared data from the State of Washington relative to roadside breath tests and subsequent corresponding BAC DataMaster tests.  The only PBT devices used were the Alco-Sensor III (n=850) and the Alco-Sensor FST (n=929).  Also, the study was limited to an “elite” group of officers whose sole responsibility was to arrest DUI suspects.  These elite officers are said to know the protocols and routines very well.  In conclusion, the authors indicate that “generalization of these results to the larger population of law enforcement officers may not be possible” because “care to detail, and the use of the PBT instruments may differ between the elite officer group and other officers.”

A total of 2,877 DUI arrests were considered, and a PBT was administered in 68.7% of the total arrests.  Five PBT results were discarded because the PBT results were highly inconsistent with the DataMaster results.  The only explanation given for discarding these five results was that those inconsistencies appeared to be due to “systematic errors, such as data entry or PBT operator error.”

The authors state that their analytical validation helps ease the way toward the use of PBT results in establishing probable cause to arrest.  Also, that their study “is not advocating that these instruments be routinely used for evidential purposes without additional quality control measures being employed (i.e., regular calibration, control standards, an appropriate time to allow dissipation of mouth alcohol, availability of printout).” However, the authors indicate that in some circumstances, PBT results should be admissible evidence.

This article is not unlike the one authored by Dr. Felix Adatsi and Michelle Glynn prior to their departure from the Michigan State Police,5 in that this article also appears to be nothing more than an attempt to publish something that looks to be a legitimate study in a legitimate scientific journal, but it is really nothing more than an effort to help law enforcement and prosecutors obtain convictions in drunk driving cases.  In this case, the author, Rod Gullberg, spent the majority of his career working for the Washington State Patrol as a breath test section research analyst.  When a person spends their life supporting a device used exclusively in the prosecution of alleged crimes, it is likely to be difficult to approach a scientific problem with any degree of objectivity.  Perhaps this is why the five outliers, where the PBT results didn’t match the DataMaster results, were simply disregarded.  It may also be why the author failed to site the major problem with handheld devices of all kinds, which is lack of slope detection.  Instead, the author simply states that a necessary quality control would be “an appropriate time to allow dissipation of mouth alcohol,” as if that will solve the problem.

There is one hidden gem in this article that can be used by Michigan practitioners.  It should be well known by now that the DataMaster DMT has improved data storage capabilities, but that this functionality has apparently been turned off in Michigan.  This information could be used by defense attorneys in a variety of ways, most notably in establishing a lack of linearity, or showing that a particular instrument has a propensity to generate a given error message, as well as a host of other quality control problems that might call the instrument’s results into question.

The State of Washington employs the data keeping and storage functionality, and the historical data from each instrument is readily available to the defense bar. The the report indicates that “the data set (for this study) was obtained from data downloaded for BAC DataMaster breath test instruments.  This data is managed by the Washington State Patrol Breath Test Section and is made freely available in the public domain through their web site.”  This begs the question—why do the Michigan State Police keep this information from the public in Michigan?

by Patrick T. Barone

Patrick T. Barone is an adjunct professor at Cooley Law School where he teaches "Drunk Driving Law and Practice."  Mr. Barone is also the co-author of two books on DUI-related issues, including Defending Drinking Drivers (James Publishing), a well-known and highly respected multi-volume national legal treatise.  He is a frequent lecturer on trial practice and drunk driving defense tactics. He can be contacted on the web at: www.baronedefensefirm.com.


1. M.C.L. §257.625c(1); M.C.L. 257.625a(2)(a)–(b); MSA 9.2325(1)(2)(a)–(b).
2. Nayak L. Polissar, Ph.D.; Wassana Suwanvijit, Ph.D. and Rod G. Gullberg, M.S.,PStat; 60 J. Forensic Sci. 482 (2015)
3. Frye v. United States, 293 F. 1013 (D.C. Cir 1923).
4. Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993).
5. Glinn, Adatsi, Comparison of the Analytical Capabilities of the BAC DataMaster and DataMaster DMT Forensic Breath Testing Devices, J. Forensic Sci., 2011.