Published under a Creative Commons license CC BY-NC-ND 4.0.

Rauchman 2025 Field Sobriety Tests And Lateral Gaze Evoked Nystagmus An Ophthalmologists Perspective

1.11MB ∙ PDF file

Download

Download

Abstract

Horizontal Gaze Nystagmus (HGN) is a type of involuntary eye movement often used by law enforcement officers during roadside sobriety tests to assess alcohol impairment. This article presents an ophthalmologist’s perspective on the scientific and clinical limitations of this practice. It explains that nystagmus can result from many causes unrelated to alcohol, including fatigue, medications, chronic illnesses, neurological conditions, and even natural variations in healthy individuals.

Despite its routine use, HGN testing at the roadside relies on subjective observation rather than accurate measurement. Officers are not trained medical professionals and do not have the tools necessary to accurately assess eye movement, measure angles of onset, or rule out alternative medical explanations. Environmental factors, such as flashing lights and moving vehicles, can further interfere with test results.

Given these concerns, this article questions the reliability of HGN as evidence in DUI cases and proposes a practical solution: requiring clear video recordings of the test to allow expert medical review. While impaired driving remains a serious public safety issue, enforcement tools must be both scientifically valid and legally sound. A more accurate, objective approach would help protect individual rights while preserving the integrity of DUI enforcement.

Introduction

Driving under the influence (DUI) of alcohol accounts for 10% of all arrests in the USA (Gjerde & Jamt, 2025). A significant percentage of traffic fatalities involve intoxicated drivers (National Highway Traffic Safety Administration, 2022). The consumption of alcohol is clearly implicated in most DUIs, making this issue of considerable social, legal, and medical significance. According to the 2022 National Survey on Drug Use and Health, 29.5 million people aged 12 and older had Alcohol Use Disorder, demonstrating that alcohol abuse is a significant social problem (National Institute on Alcohol Abuse and Alcoholism (NIAAA, 2025).

Burns provides a comprehensive summary of field sobriety research, documenting that police officers’ examinations of suspected alcohol-impaired drivers include the administration of the Standard Field Sobriety Tests (SFSTs) (Burns, 2003). These tests include Horizontal Gaze Nystagmus (HGN), the Walk-and-Turn test, and the One-Leg-Stand test (Burns, 2003).

While blood and breath analyses of alcohol levels in drivers are crucial in DUI cases, this perspective focuses on the value and limitations of Horizontal Gaze-Evoked Nystagmus (HGEN) and related eye findings from an ophthalmologic perspective. Although the Walk-and-Turn and One-Leg-Stand tests are noted, the primary emphasis is on how interpretation intersects with ocular physiology, measurement challenges, and confounders relevant to HGN. Legal standards are acknowledged but not analyzed in depth.

SFST background and the Colorado validation Work

Burns references the accuracy of DUI testing by law enforcement in earlier studies by Burns and Moskowitz and by Tharp, Burns, and Moskowitz (Burns, 2003; Burns & Moskowitz, 1977; Tharp, Burns, & Moskowitz, 1981). The most exhaustive field test, often treated as representative, is Burns and Anderson, funded by the Colorado Office of Transportation Safety and associated with NHTSA initiatives (Burns & Anderson, 1995). These studies underpin current guidance but contain assumptions and field constraints that warrant scrutiny from a neuro-ophthalmic perspective. Diagnosing gaze-evoked nystagmus in the field is challenging and, in clinical practice, is performed under standardized conditions by trained eye-care professionals.

There is a high correlation between individuals who fail a field sobriety test and those arrested for elevated blood or breath alcohol levels, but an important question remains: What percentage of drivers pulled over for routine moving violations already have elevated BAC? If that percentage is high, the field sobriety test may add little or no incremental information. The validation literature does not directly address this base-rate problem (Burns & Anderson, 1995; Burns & Moskowitz, 1977; Tharp et al., 1981).

Critical Appraisal of NHTSA’s Horizontal Gaze Nystagmus: The Science and the Law

This NHTSA and National Traffic Law Center guide is widely cited as a compendium of prior research and recommendations on HGN (National Traffic Law Center, 2021). Notably, its acknowledgments list a range of contributors but no ophthalmologists, despite reliance on eye-movement assessment. The introduction asserts that “the consumption of alcohol or other drugs hinders the ability to correctly control eye muscles. The resulting abnormal eye movements are readily identifiable by properly educated and trained observers such as law enforcement officers”. While alcohol can cause horizontal gaze-evoked nystagmus, determining the presence and type of nystagmus is a complex medical assessment that lies beyond the scope of roadside training.

The guide characterizes HGN as “three separate assessments of independent eye movements: smooth pursuit, nystagmus at maximum lateral gaze, and onset of nystagmus prior to full deviation” (National Traffic Law Center, 2021). As defined in neuro-ophthalmic texts, however, evaluating gaze-evoked nystagmus requires, at minimum, confirmation of fixation and visual acuity, plus differentiation from numerous physiologic and pathologic causes (American Academy of Ophthalmology, 2022 to 2023; Thurtell, 2013). The Science section simultaneously concedes that vestibular-related eye movements are common but “are not assessed by law enforcement,” and that “neither fixation ability nor visual acuity are assessed” (National Traffic Law Center, 2021). Those omissions undermine reliability because they are foundational steps in any clinical evaluation (American Academy of Ophthalmology, 2022 to 2023; Thurtell, 2013).

The same section notes that distinguishing eye-movement types often requires specialized recording instruments, tools rarely available at the roadside, which further limits accuracy (National Traffic Law Center, 2021). In addition, terms such as Alcohol Gaze Nystagmus (AGN) and Positional Alcohol Nystagmus (PAN) are not standard in ophthalmic literature and imply alcohol-specific patterns that are not recognized clinically (National Traffic Law Center, 2021). Finally, although the guide states the HGN test is “very easy to administer,” even specialists find careful assessment of HGEN technically demanding. Protocol elements such as moving the target at about 10 degrees per second and judging onset before about 45 degrees presuppose timing and angle-measurement capabilities that officers do not have (National Traffic Law Center, 2021).

A related policy inconsistency is notable. State DMVs uniformly screen visual acuity for licensure but do not screen for nystagmus. If nystagmus evaluation were essential to driving safety, a licensing-stage program would presumably exist. The government cannot simultaneously deem visual acuity essential at licensure while treating roadside nystagmus assessment as both easy and decisive, yet omit it from licensing standards.

Definitions and clinical context: GEN, HGN, and OKN

• Gaze-evoked nystagmus (GEN): rhythmic drift of the eyes back toward primary position with corrective saccades when holding an eccentric gaze. Low-amplitude endpoint nystagmus can be physiologic at extreme gaze. Sustained, large, or asymmetric forms are typically pathologic and should prompt evaluation (American Academy of Ophthalmology, 2022 to 2023; Thurtell, 2013).

• Horizontal Gaze Nystagmus (HGN or HGEN): the lateral tracking sign emphasized during SFST. Some protocols associate angle-of-onset thresholds with alcohol effects (National Traffic Law Center, 2021).

• Optokinetic nystagmus (OKN): a normal response to moving visual scenes, such as passing headlights, which can mimic HGN during roadside testing (American Academy of Ophthalmology, 2022 to 2023).

Given the diversity of nystagmus types and overlap in appearance, even trained ophthalmologists may find differentiation challenging without standardized conditions and instrumentation (American Academy of Ophthalmology, 2022 to 2023; Thurtell, 2013).

Measurement Limits At The Roadside: Angle Of Onset And Stimulus Control

HGN protocols put weight on estimating the angle of onset and controlling the speed of the moving target. Training materials describe moving the target at roughly 10 degrees per second and noting the onset prior to approximately 45 degrees (National Traffic Law Center, 2021). Without instruments to time motion or measure angles, these are estimates, not measurements. That invites variability and bias. Objective capture, such as video-oculography, allows later expert review and reduces subjectivity (Ritter, Bertolini, Straumann, & Bögli, 2020).

Environmental Confounds In Nighttime Stops

Roadside guidance instructs officers to avoid facing flashing police lights or passing traffic when conducting HGN or GEN because OKN can be induced by moving luminance patterns and is not alcohol-specific (American Academy of Ophthalmology, 2022 to 2023; National Traffic Law Center, 2021). In nighttime traffic environments, the likelihood of OKN contaminating observations increases. Tests should be conducted in the absence of such stimuli to minimize misclassification.

Prevalence And Population Considerations

If HGN or a visually similar GEN were rare in the general population, it might serve as a useful screening tool. If not, specificity erodes. The Leicestershire survey includes visually impaired cohorts (Sarvananthan et al., 2009). These are presumably not drivers. The estimate of 24 per 10,000 for the frequency of nystagmus is without foundation. The survey even notes that the population of Leicestershire is 925,000 people. There was no effort to systematically evaluate this population. Laboratory work demonstrates physiologic GEN at small gaze angles in many healthy observers. In particular, Whyte and colleagues reported physiologic GEN in 21% at 10 degrees and 34% at 20 degrees using binocular infrared video-oculography (Whyte, Petrock, & Rosenberg, 2010). Ritter and colleagues found that most healthy individuals display GEN and rebound nystagmus at modest eccentricities. In one dataset, 71% exhibited GEN at 30 degrees (Ritter et al., 2020). These eccentricities lie squarely within those probed during roadside HGN, which implies a substantial false-positive risk when onset angles are judged subjectively (Ritter et al., 2020; Whyte et al., 2010).

Medical Confounders Commonly Encountered in the Forensic Settings

• Chronic alcoholism: may produce cerebellar degeneration and associated nystagmus independent of acute intoxication (Lau, Campos, Gai, et al., 2024). Distinguishing acute alcohol-related HGN from chronic alcoholism-related nystagmus is challenging. Not all individuals with alcoholism have recently consumed alcohol when stopped.

• Medications: benzodiazepines are prevalent and can affect oculomotor control (Maust, Lin, & Blow, 2019).

• Fatigue: can impair oculomotor control and alter eye-movement stability (Connell, Thompson, Turuwhenua, Srzich, & Gant, 2017).

• Vestibular disorders: NHANES 2001 to 2004 data estimate objective vestibular dysfunction in about 35% of U.S. adults aged 40 and older. This corresponds to about 69 million people and indicates that vestibular contributions to eye movements are common in drivers (Agrawal, Carey, Della Santina, Schubert, & Minor, 2009).

• Stimulants and exposures: the NHTSA guide itself acknowledges caffeine can induce nystagmus in those with vestibular problems (National Traffic Law Center, 2021).

• Head trauma: post-crash evaluations must consider trauma-related nystagmus when accidents precede testing (Rauchman et al., 2023).

These factors are plausibly encountered among DUI arrestees and can confound HGN interpretation.

Practical Qualifications and Training Limits

Some legal resources imply that limited officer training suffices to diagnose nystagmus. In clinical practice, evaluation begins with fixation and visual acuity, often followed by a targeted examination including a vestibular assessment to classify nystagmus (American Academy of Ophthalmology, 2022 to 2023; Thurtell, 2013). Such assessment typically requires specialized training and controlled conditions. One could imagine expanded training and instrumentation for roadside use, yet in practice, this is rarely feasible at the curb and risks conflating screening with diagnosis (American Academy of Ophthalmology, 2022 to 2023; National Traffic Law Center, 2021; Thurtell, 2013).

Independence of Tests within SFST

Combined battery scoring assumes independence across tasks. Vertigo or imbalance that accompanies nystagmus may degrade performance on Walk-and-Turn or One-Leg-Stand, which entangle outcomes and compromise interpretation when tests are treated as independent contributors to impairment.

Predictive Value And Base Rates: What Would A Validating Study Require?

It is not enough to note that alcohol can cause HGEN. To demonstrate incremental value, we must know the pretest probability of illegal BAC among drivers stopped for routine moving violations. A properly controlled design would breath-test all such drivers, regardless of HGN, and then determine whether roadside HGN adds discrimination beyond that base rate. If the pretest base rate is already high, HGN contributes little predictive value. If it is low, any added value must be demonstrated empirically. A medical test is not meaningful if it is used merely to manufacture probable cause, which is a legal standard rather than a physiologic one.

When HGN is Present but BAC is Negative: Duty of Care

Drivers who display nystagmus yet have negative breath or chemical tests may have non-alcohol causes, such as vestibular disease, medication effects, or central nervous system pathology. In clinical practice, such findings would prompt neuro-ophthalmic and vestibular evaluation and, when indicated, neuroimaging. Current roadside use provides no mechanism to inform or refer such individuals. Establishing a path for notification and medical follow-up would better align enforcement with public health.

Conclusion

From an ophthalmologist’s perspective, the roadside interpretation of HGN is constrained by four issues. First, officers estimate the angle of onset without instruments (National Traffic Law Center, 2021; Ritter et al., 2020). Second, environmental OKN can contaminate observations (American Academy of Ophthalmology, 2022 to 2023; National Traffic Law Center, 2021). Third, non-alcohol physiologic GEN at small angles is common in healthy people (Ritter et al., 2020; Sarvananthan et al., 2009; Whyte et al., 2010). Fourth, medical confounders such as chronic alcoholism, medications, fatigue, and trauma are prevalent (Agrawal et al., 2009; Connell et al., 2017; Lau et al., 2024; Maust et al., 2019; Rauchman et al., 2023). As a result, horizontal gaze-evoked nystagmus cannot be reliably assessed in drivers pulled over for suspected DUIs. Simply stated, this is a complex medical evaluation that is beyond the scope of law enforcement at the curbside.

In addition, there are many causes of horizontal gaze nystagmus that occur independent of alcohol consumption, and several of these conditions are common in the driving population. That makes any uninstrumented nystagmus observation a substantial confounding variable (Agrawal et al., 2009; Ritter et al., 2020; Whyte et al., 2010). Related vestibular symptoms, such as vertigo, which can influence eye-movement findings, cannot be adequately assessed by officers during a roadside stop (American Academy of Ophthalmology, 2022 to 2023; National Traffic Law Center, 2021). Notably, state DMVs check visual acuity to establish minimum licensing requirements. These same agencies do not require or track nystagmus testing, which underscores the absence of a public-policy framework for its roadside use.

DUIs remain a major public-safety and political concern, and there is strong public demand to keep impaired drivers off the road. In that context, this paper has presented scientific evidence that questions the value of HGN in DUI arrests. As a pragmatic compromise, short of ideal laboratory-grade instrumentation, I recommend making a clear, front-facing video of the subject’s eyes and the officer’s performance of the test a standard protocol. When body-camera footage has sufficient resolution, it should be made available to all parties so that qualified experts can review the recording and provide an objective opinion (Ritter et al., 2020). This approach is not perfect, for reasons discussed above, but it would improve transparency, reduce subjectivity, and better align the process with clinical standards.

Ultimately, this is not purely a scientific question. It is also a policy question that implicates public safety. Compromise is preferable to a deadlocked debate. Law enforcement, government agencies, prosecutors, and medical experts can work toward a workable consensus that prioritizes safety while grounding decisions in physiology, measurement science, and fair procedure.

Disclosures

The author is an expert consultant in DUI-related legal cases.

References

Agrawal, Y., Carey, J. P., Della Santina, C. C., Schubert, M. C., & Minor, L. B. (2009). Disorders of balance and vestibular function in U.S. adults: Data from the National Health and Nutrition Examination Survey, 2001 to 2004. Archives of Internal Medicine, 169(10), 938–944. https://doi.org/10.1001/archinternmed.2009.66

American Academy of Ophthalmology. (2022 to 2023). Basic and Clinical Science Course, Section 5: Neuro-ophthalmology, Chapter 10: Nystagmus or Spontaneous Eye Movement Disorders. American Academy of Ophthalmology.

Burns, M. (2003). An overview of field sobriety test research. Perceptual and Motor Skills, 97(3_suppl), 1187–1199. https://doi.org/10.2466/pms.2003.97.3f.1187

Burns, M., & Anderson, R. (1995). A Colorado validation study of the Standardized Field Sobriety Test (SFST) battery. Colorado Department of Transportation.

Burns, M., & Moskowitz, H. (1977). Psychophysical tests for DWI arrest. U.S. Department of Transportation, National Highway Traffic Safety Administration.

Connell, C. J., Thompson, B., Turuwhenua, J., Srzich, A., & Gant, N. (2017). Fatigue-related impairments in oculomotor control are prevented by norepinephrine-dopamine reuptake inhibition. Scientific Reports, 7, 42726. https://doi.org/10.1038/srep42726

Hallvard Gjerde, Ragnhild Elén Gjulem Jamt, Alcohol and drug detection rates in road traffic: An international comparison, Forensic Science International: Reports, Volume 12, 2025, 100427, ISSN 2665-9107, https://doi.org/10.1016/j.fsir.2025.100427

Lau, H., Campos, A., Gai, D., et al. (2024). Alcoholic cerebellar degeneration. Radiopaedia.org. https://doi.org/10.53347/rID-80325

Maust, D. T., Lin, L. A., & Blow, F. C. (2019). Benzodiazepine use and misuse among adults in the United States. Psychiatric Services, 70(2), 97–106. https://doi.org/10.1176/appi.ps.201800321

National Highway Traffic Safety Administration. (2022, April). Traffic Safety Facts 2020 data: Alcohol-impaired driving (Report No. DOT HS 813 294). U.S. Department of Transportation, National Highway Traffic Safety Administration, National Center for Statistics and Analysis. https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/813294

National Institute on Alcohol Abuse and Alcoholism. (November 1, 2025). Alcohol use disorder: AUD in the United States: Age groups and demographic characteristics. https://www.niaaa.nih.gov/alcohols-effects-health/alcohol-topics/alcohol-facts-and-statistics/alcohol-use-disorder-aud-united-states-age-groups-and-demographic-characteristics

National Traffic Law Center, National District Attorneys Association. (2021). Horizontal gaze nystagmus: The science and the law: A resource guide for judges, prosecutors, and law enforcement (2nd ed.).

Rauchman, S. H., Zubair, A., Jacob, B., Rauchman, D., Pinkhasov, A., Placantonakis, D. G., & Reiss, A. B. (2023). Traumatic brain injury: Mechanisms, manifestations, and visual sequelae. Frontiers in Neuroscience, 17, 1090672. https://doi.org/10.3389/fnins.2023.1090672

Ritter, M. S., Bertolini, G., Straumann, D., & Bögli, S. Y. (2020). Prevalence and characteristics of physiological gaze-evoked and rebound nystagmus: Implications for testing their pathological counterparts. Frontiers in Neurology, 11, 547015. https://doi.org/10.3389/fneur.2020.547015

Sarvananthan, N., Surendran, M., Roberts, E. O., Jain, S., Thomas, S., Shah, N., Proudlock, F. A., Thompson, J. R., McLean, R. J., Degg, C., Woodruff, G., & Gottlob, I. (2009). The prevalence of nystagmus: The Leicestershire nystagmus survey. Investigative Ophthalmology & Visual Science, 50(11), 5201–5206. https://doi.org/10.1167/iovs.09-3486

Tharp, V. J., Burns, M., & Moskowitz, H. (1981). Development and field test of psychophysical tests for DWI arrest (DOT HS 806 475). U.S. Department of Transportation, National Highway Traffic Safety Administration.

Thurtell, M. J. (2013). The challenge of nystagmus. Journal of Neuro-Ophthalmology, 33(2), e7. https://doi.org/10.1097/WNO.0b013e318280d7e0

Whyte, C. A., Petrock, A. M., & Rosenberg, M. (2010). Occurrence of physiologic gaze-evoked nystagmus at small angles of gaze. Investigative Ophthalmology & Visual Science, 51(5), 2476–2478. https://doi.org/10.1167/iovs.08-3241

Abstract

Inconsistent exhaled volume requirements across breath alcohol analyzers create a significant hurdle when comparing breath alcohol concentration (BrAC) from various analyzers. Vast differences in exhaled volume requirements among analyzers mean reliable BrAC comparisons cannot be made from one analyzer to another. Forensic scientists and manufacturers of breath alcohol analyzers must consider the ramifications of inconsistent exhaled volume requirements in the legal context for fair and reliable comparisons of BrAC to be made.

The Need For Standardization Of Exhaled Volume In Breath Alcohol Testing

144KB ∙ PDF file

Download

Download

Introduction

Reliable measurements of BrAC are crucial in the legal context where a person's guilt or innocence and potential incarceration are at stake. However, determining an appropriate exhaled volume sampling requirement is more complex than it may seem (1–5). One challenge in defining the appropriate exhaled volume sampling requirement is that BrAC is heterogeneous and continues to rise throughout exhalation (6–8). 

Exhaled volume requirements amongst evidential breath alcohol analyzers vary widely. Vast differences in requirements mean that a subject could be under the legal BrAC limit for driving on one analyzer and simultaneously over the legal limit on another. 

For example, Figure 1 shows an expirogram of a subject who blew into the Minnesota version of the DataMaster DMT (DMT) (Intoximeters, St. Louis, MO). The expirogram shows what the subject’s BrAC would have been if tested with different evidential breath alcohol analyzers.

Table 1 shows different outcomes based on various breath alcohol analyzers. In two analyzers, the subject would have been under the legal driving limit of 0.08 g/210L, while in one analyzer, the subject would have been over the legal limit. 

Discussion

In breath alcohol testing, manufacturers have implemented minimum exhaled volume standards (usually 1.1 - 1.5 liters) but have paid little attention to the impact of the upper limit of exhaled volume. Without consistent standards for exhaled volume, situations will arise where a subject will be under the legal BrAC limit for driving on one analyzer while being over the legal limit on another. In the legal context, this raises questions about fairness based on the analyzer and exhaled volume parameters selected.

Conclusion

Breath alcohol analyzer manufacturers and forensic scientists must consider the impact of the maximum exhaled volume when comparing BrAC values. The lack of standardization of exhaled volume means that reliable BrAC comparisons cannot be made from one analyzer to the next.

Disclosures

The author serves as an expert witness in forensic toxicology cases.

References

1. Wilson HK. Breath analysis. Physiological basis and sampling techniques. Scand J Work Environ Health [Internet]. 1986 Jun;12(3):174–92. Available from: https://www.ncbi.nlm.nih.gov/pubmed/3749832

2. Lawal O, Ahmed WM, Nijsen TME, Goodacre R, Fowler SJ. Exhaled breath analysis: a review of “breath-taking” methods for off-line analysis. Metabolomics [Internet]. 2017 Aug 19;13(10):110. Available from: http://dx.doi.org/10.1007/s11306-017-1241-8

3. Beauchamp JD, Pleil JD. Simply breath-taking? Developing a strategy for consistent breath sampling. J Breath Res [Internet]. 2013 Dec;7(4):042001. Available from: http://dx.doi.org/10.1088/1752-7155/7/4/042001

4. Lindberg L, Jones AW. The advantages of standardizing exhaled breath-alcohol concentration to a reference respiratory gas-water vapor. J Breath Res [Internet]. 2022 Nov 23;17(1). Available from: http://dx.doi.org/10.1088/1752-7163/aca21b

5. Vosk T, Forrest ARW, Emery A, McLane LD. The measurand problem in breath alcohol testing. J Forensic Sci. 2014 May;59(3):811–5. Available from: http://dx.doi.org/10.1111/1556-4029.12406

6. Anderson JC, Hlastala MP. The alcohol breath test in practice: effects of exhaled volume. J Appl Physiol. 2019 Jun 1;126(6):1630–5. Available from: http://dx.doi.org/10.1152/japplphysiol.00726.2018

7. Hlastala MP. Paradigm shift for the alcohol breath test. J Forensic Sci [Internet]. 2010 Mar 1;55(2):451–6. Available from: http://dx.doi.org/10.1111/j.1556-4029.2009.01269.x

8. Simpson D, Kerby J, Kerby S. Varying Length of Expirational Blow and End Result Breath Alcohol. International Journal of Drug Testing. 2007;3.

9. Bishop SC, Johnson G, Smith L, Fiorentino DD, Garcia T, Garcia R, et al. Manual versus automatic sampling variations of a preliminary alcohol screening device. J Anal Toxicol [Internet]. 2009 Oct;33(8):521–4. Available from: http://dx.doi.org/10.1093/jat/33.8.521

10. Iowa DataMaster DMT Operating Training Manual [Internet]. Iowa Division of Criminal Investigation Alcohol Section; 2021. Available from: https://breathalcohol.iowa.gov/files/Operating_the_DataMaster_DMT_version_3.0.pdf

11. Minnesota Bureau of Criminal Apprehension. DMT Operator Training Manual [Internet]. Minnesota Department of Public Safety; 2019. Available from: https://dps.mn.gov/divisions/bca/bca-divisions/forensic-science/Documents/DMT%20Operator%20Manual.pdf

Abstract

The breath alcohol test (BAT) is the most commonly used forensic test to estimate a person’s blood alcohol concentration (BAC) in the US. Despite individual states adopting per se laws making driving while having ≥0.08% BAC (or ≥0.08 g/210L breath) illegal, the US lacks national standards for breath alcohol testing. The lack of national standards for the BAT reduces confidence in the results. Many states do not implement basic quality assurance standards, such as obtaining duplicate breath samples. One way to overcome this lack of quality assurance is to tie federal funding from the Transportation Equity Act for the 21st Century (TEA-21) to quality assurance practices for the BAT.

The Need For National Standards In Breath Alcohol Testing

123KB ∙ PDF file

Download

Download

Introduction

All states throughout the US  have per se laws that establish that driving is a crime while having a BAC of ≥0.08% (or ≥0.08 g/210L breath). Yet, there are no national quality assurance standards mandated for the BAT. Each state establishes its own breath alcohol testing program. There are published recommendations, as described below, but no federally mandated standards.  

In 1997, the Federal Government set up Section 1404 of TEA-21, establishing a new program of incentive grants (Under Section 163 of Chapter 1 of Title 23) to encourage states to establish a 0.08% BAC as the legal limit for drunk driving offenses.1  The grant authorized $500 million, over six years, to the states for passing 0.08% BAC per se laws. This was the Federal Government’s “carrot and stick” way of getting a national 0.08% BAC per se law passed in each state without a federal law or mandate.

The Federal Government has used the TEA-21 many times over the years to coax the states into implementing programs such as seatbelt laws, open container laws, zero tolerance for drinking drivers under 21, and many others.

The states have all passed the 0.08% BAC standard, and the National Transportation Safety Board (NTSB) continues to make recommendations to the National Highway Traffic Safety Administration (NHTSA) regarding safe BAC driving limits. For example, in 2013, they sought legislative authority to award incentive grants to states to encourage a new national per se BAC of 0.05% or lower.2

The Problem with Per Se Laws

Currently, per se laws mandate that a driver is in violation of the law if they drive with a BAC of 0.08% or greater.  It does not matter how well or how badly a person is driving.  The problem with per se laws is that the driver has no way to know when they are in violation of the law.   

Cars have speedometers to let drivers know when they are driving too fast but do not have breath alcohol analyzers to let a person know when they are above the per se limit.

There are three basic per se limits in the United States for BAC:

• 0.08% for persons 21 years old or older driving a private vehicle

• 0.04% for persons 21 years old or older driving a commercial motor vehicle

• 0.02% for persons under 21 driving a vehicle

In most cases, the evidence of the alcohol concentration in court is a breath test result.  The state’s per se laws and implied consent laws created “shortcuts” for the admissibility of the breath test result. These laws allow prosecutors to bypass the standard rules for the admissibility of scientific evidence in a criminal court. 

No scientific foundation is established for the admissibility of the breath test result in driving while intoxicated (DWI) trial.  The way the laws are written allows the breath test result to go into court with very little support for the result.

The Problem with Inconsistent Standards

Most states legislate that the breath test result is admissible if the established procedures are followed.  The problem is that the procedures, breath testing instruments, protocols, calibration, sampling, and all other aspects of a breath alcohol testing program vary drastically from state to state. 

In 2008, the National Safety Council (NSC), Committee on Alcohol and Other Drugs established what they deemed, “…the basic elements necessary for establishing quality assurance and fitness-for-purpose in evidential breath alcohol measurements.”3

The NSC published recommendations that the states should follow for a quality and minimum acceptable breath alcohol testing program to support the per se laws in the states.  The recommendations are as follows:

• Instruments should be operated and tests administered by trained and qualified BAT instrument operators.

• Instruments should be approved by an appropriate agency and, if used in the United States, also appear on the National Highway Traffic Safety Administration’s Conforming Products List.

• Testing protocols should employ a minimum pre-exhalation mouth alcohol deprivation period of 15 minutes.

• Breath alcohol measurements should be conducted on at least duplicate independently exhaled end-expiratory breath samples; the breath sample results should agree with the applicable established and documented criteria.

• At least one control analysis should be performed as part of each subject test sequence as an assessment of within-run accuracy and/or verification of calibration.

• An ambient air blank/analysis should be performed before and after each breath and control sample analytical measurement.

• Any non-compliance or non-conformity with established and documented evidential test sequence protocol criteria should require the performance of a completely new evidential test sequence.

• Printout of all completed tests should show the results of all breath samples, ambient air analysis/blanks and control analyses performed during a subject test sequence.

• Periodic calibration, verification of calibration and/or certification of instruments must be performed in conformance with the documented and approved protocol recognized by the applicable jurisdiction.

• Periodic recertification of breath test instrument operators should be done in compliance with documented and established training criteria recognized by the applicable jurisdiction at least every five years.

A review of breath test cases from across the country shows that many states fail to comply with the recommendations of the NSC. 

In 2008, the NSC made recommendations based on the legal ramifications of a BAT. They said:

The significant weight assigned to breath alcohol results, along with the serious consequences arising from conviction on an impaired driving offense require evidential breath alcohol testing programs to implement appropriate quality assurance measures.

In addition, in 1994, Dr. Kurt M. Dubowski published Quality Assurance in Breath–Alcohol Analysis.4  He listed six problem areas with state breath alcohol programs. The list includes:

• Inadequate rules and regulations

• Lack of a comprehensive quality assurance program

• Lack of control test(s) accompanying every subject test

• Failure to observe and adequately document a proper pretest deprivation-observation period

• Failure to test duplicate breath specimens

• Lack of periodic personnel training

In light of per se DWI laws, a reading above the legal limit often becomes the sole piece of evidence needed for a conviction. National standards for the BAT become crucial to ensure fairness. Standards help to ensure accuracy and reliability across jurisdictions, preventing potential wrongful convictions due to varying testing procedures and equipment.

The Solution: Mandatory Quality Assurance Standards

The lack of national standards continues to cast a shadow of uncertainty over the accuracy and fairness of BAT programs across the country. A solution to this problem is integrating quality assurance protocols into the TEA-21 incentive structure.

By tying federal funding to adherence to national standards, states will be incentivized to implement best practices and ensure a more consistent, reliable, and fair approach to the BAT nationwide.

Conclusion

The state of breath alcohol testing in the United States is characterized by a patchwork of inconsistent standards and inadequate quality assurance practices. The lack of uniformity in the BAT undermines its accuracy and reliability in a forensic situation. Tying federal TEA-21 funding to quality assurance protocols for the BAT would encourage states to adopt more rigorous standards and inspire greater confidence in the results.

Disclosures

The author serves as an expert witness in forensic breath alcohol cases.

References