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Introduction
Drugged-driving prosecutions in Michigan present a fundamentally different evidentiary landscape than traditional alcohol-impaired driving cases. The standardized field sobriety test (SFST) battery was developed and validated to discriminate alcohol-impaired drivers from sober drivers, not to identify drug-impaired drivers; the breath testing instruments measure ethanol, not tetrahydrocannabinol (THC), benzodiazepines, opioids, or any other class of drug; and the principal alternative offered by law enforcement—the twelve-step Drug Recognition Expert (DRE) protocol—has been the subject of a published Michigan Court of Appeals decision holding that DRE testimony purporting to conclude that a defendant was operating a vehicle while impaired by marijuana is inadmissible under MRE 702 due to a lack of scientific reliability. People v Bowden, 344 Mich App 171 (2022).
The legal and scientific landscape was further reshaped by Michigan's voter-approved decriminalization and regulation of recreational marijuana under the Michigan Regulation and Taxation of Marihuana Act (MRTMA), MCL 333.27951 et seq.; by the Michigan Impaired Driving Safety Commission's 2019 finding that there is no scientifically supported threshold of delta-9 THC bodily content that would be indicative of impaired driving; and by NHTSA's own July 2017 acknowledgment in Marijuana-Impaired Driving: A Report to Congress that no scientifically validated methods exist to detect marijuana-impaired driving with the same reliability as alcohol-impaired testing. The 2023 randomized clinical trial published in JAMA Psychiatry by Marcotte and colleagues then provided peer-reviewed evidence that completely sober subjects frequently fail the standardized field sobriety tests.
I have lectured on drugged driving since 2013, served as President of the Criminal Defense Attorneys of Michigan (CDAM) during the period in which the legal status of marijuana was actively shifting in Michigan, and currently serve on the Board of Directors of the Michigan Association of OWI Attorneys (MIAOWIA). MIAOWIA, jointly with the Michigan Medical Marihuana Association, filed an amicus curiae brief in the Bowden appeal that contributed to the Court of Appeals' rejection of the DRE protocol as an evidentiary basis for marijuana-impairment opinion testimony. This page describes the science and statutory framework that govern drugged-driving prosecutions in Michigan, the technical deficiencies in the twelve-step DRE protocol identified in the peer-reviewed literature and the published case law, the specific issues that arise in marijuana cases, and the categories of analytical work that I perform as an expert witness in drug-impaired-driving matters.
Michigan's Statutory Framework for Drug-Impaired Driving
The principal Michigan statute governing drug-impaired driving is MCL 257.625(1)(a), which prohibits operating a motor vehicle while under the influence of alcoholic liquor, a controlled substance, or other intoxicating substance, or any combination of those substances. A separate per se provision, MCL 257.625(8), prohibits operating with any amount of a Schedule 1 controlled substance or cocaine in the body, but the Michigan Supreme Court's decision in People v Koon, 494 Mich 1 (2013), held that this per se provision does not apply to a registered medical marijuana patient.
The Michigan Regulation and Taxation of Marihuana Act, MCL 333.27951 et seq., enacted by voter initiative in 2018, generally decriminalized adult use of marijuana. MCL 333.27954 prohibits operating a vehicle "under the influence of marihuana," but it does not proscribe operating a vehicle with any amount of THC in the body. Having THC in the body is therefore no longer, by itself, indicative of unlawful activity under Michigan law. The Michigan Supreme Court reinforced this principle in People v Armstrong, ___ Mich ___ (2025) (Docket No. 165233), in which the Court overruled People v Kazmierczak, 461 Mich 411 (2000), and held that the smell of marijuana, by itself, no longer provides police with sufficient probable cause to search a vehicle. The Court of Appeals had reached a similar conclusion in People v Armstrong, 344 Mich App 286 (2022), where it held that the odor of marijuana is relevant to the totality-of-the-circumstances test and can contribute to a probable-cause determination, but the smell of marijuana, by itself, does not give rise to probable cause unless it is combined with other factors that bolster the concern about illegal activity that may flow from the smell of marijuana.
The Michigan Impaired Driving Safety Commission was established within the Michigan State Police to research and recommend a scientifically supported threshold of delta-9 THC bodily content for per se impaired driving. The Commission's March 2019 Report from the Impaired Driving Safety Commission concluded, after considering the peer-reviewed literature and expert testimony, that based on the total body of knowledge presently available, there is no scientifically supported threshold of delta-9 THC bodily content that would be indicative of impaired driving, because there is a poor correlation between driving impairment and blood (plasma) levels of delta-9 THC at the time of blood collection. The Commission accordingly declined to recommend any per se THC limit. The Michigan legislature has, to date, declined to enact one.
The DRE Protocol: Origin and Structure
The Drug Recognition Expert protocol—sometimes more accurately described as Drug Recognition Evaluator—is a twelve-step procedure developed by the Los Angeles Police Department in the 1970s, adapted by NHTSA in the early 1980s, and administered nationally since 1989 by the International Association of Chiefs of Police (IACP) in cooperation with NHTSA. The protocol claims to enable a trained officer not only to identify whether a driver is drug-impaired, but to identify the specific category of drug (or combination of categories) responsible for the impairment.
The twelve steps of the DRE protocol, as set out in the IACP-approved DRE Student Manual and described in the 2018 IACP Drug Recognition Expert Course, Instructor Guide, are: (1) breath alcohol test; (2) interview of the arresting officer; (3) preliminary examination and first pulse; (4) eye examination, including horizontal gaze nystagmus, vertical gaze nystagmus, and lack of convergence; (5) divided-attention psychophysical tests, including the Modified Romberg Balance, the walk-and-turn, the one-leg stand, and the finger-to-nose; (6) vital-signs examination, including blood pressure, temperature, and pulse; (7) darkroom examination of pupil size under three lighting conditions, plus an oral and nasal cavity inspection; (8) examination of muscle tone; (9) examination for injection sites and a third pulse; (10) suspect statements and other observations; (11) opinion of the evaluator as to the category or categories of drug involved; and (12) toxicological examination of a blood or urine sample.
The structural premise of the protocol, as Greg Kane analyzed in his peer-reviewed critique Kane, G. The methodological quality of three foundational law enforcement drug influence evaluation validation studies. J Negat Results BioMed 12, 16 (2013). https://doi.org/10.1186/1477-5751-12-16, is that a failed SFST proves impairment; that breath alcohol testing rules out alcohol as the cause of that impairment; that medical evaluation by the DRE officer rules out a medical cause; that the DRE physical examination identifies the category of drug responsible; and that toxicological examination then circles back to confirm the SFST's proof of impairment because the drug found in the toxicology screen was within the predicted category. Kane's central observation is that this is circular reasoning: if a drug in the predicted category is found, the prediction is treated as confirmed; if a drug in any other category is found, some validation calculations treat the result as still confirmatory because, after all, a drug was present.
The Bowden Decision and Its Implications
The leading Michigan authority on the admissibility of DRE testimony in marijuana cases is People v Bowden, 344 Mich App 171 (2022). Cara Bowden was charged with operating while intoxicated, first offense, after a December 1, 2020, traffic stop in Ottawa County. During the stop, she was subjected to the twelve-step DRE protocol, and the deputy who conducted the evaluation opined that she was impaired by cannabis to a degree that made it unsafe and unlawful for her to be operating a motor vehicle. The State filed a pretrial motion to qualify the deputy as an expert witness. After an evidentiary hearing in February 2021, the trial court granted the motion. The 20th Circuit Court of Ottawa County affirmed in July 2021. The Michigan Court of Appeals granted leave and ultimately reversed in a published 2-1 decision.
The Court of Appeals held that the trial court abused its discretion in admitting the DRE testimony under MRE 702, and addressed the admissibility question in terms drawn directly from Daubert v Merrell Dow Pharmaceuticals, Inc, 509 US 579 (1993), as adopted in Michigan by Gilbert v DaimlerChrysler Corp, 470 Mich 749 (2004). Under MRE 702 and Gilbert, the trial court must act as a gatekeeper to ensure that the testimony is based on sufficient facts or data, that the testimony is the product of reliable principles and methods, and that the witness has applied the principles and methods reliably to the facts of the case. The Court of Appeals found that the record contained no evidence demonstrating the DRE protocol's ability to reliably assess marijuana-induced impairment or its correlation with unsafe driving.
The Court of Appeals expressly rejected the prosecution's reliance on the studies presented at the Daubert hearing. The studies addressed the DRE protocol's accuracy in detecting the presence of substances in a person's blood, but neither of the submitted reports purported even to address the question of how particular levels of marijuana impacted a person's ability to drive or rendered a person impaired. The determination under the DRE protocol that a person is impaired and unable to safely drive a car appears, in the Court's analysis, to be ultimately based on the DRE officer's subjective judgment, and there is no evidence in the record that the ability of a person to make such a judgment based on the application of the DRE protocol has been tested to demonstrate the accuracy and validity of reaching such a conclusion on a person's level of impairment due to marijuana. The Court fortified its holding by citing NHTSA's 2017 Report to Congress, which acknowledged that there are no current evidence-based methods to detect marijuana-impaired driving as there are for alcohol-impaired driving.
Although Bowden arose in a marijuana case and the Court of Appeals' reasoning is rooted in the particular scientific deficiencies of the DRE protocol as applied to cannabis, the analytical framework that Bowden applies—that DRE testimony cannot be admitted under MRE 702 absent record evidence of reliability, that the prosecution cannot satisfy that burden by citing studies that address only the presence of drugs rather than impairment, and that the officer's subjective judgment is not, by itself, an MRE 702 foundation—extends naturally to other drug categories. The MIAOWIA and Michigan Medical Marihuana Association amicus curiae brief filed in Bowden developed each of these arguments at length, and the Court of Appeals' opinion incorporates the substance of that critique.
The Kane Peer-Reviewed Critique of the DRE Validation Studies
The most substantial peer-reviewed critique of the DRE validation studies on which prosecutors rely is Greg Kane's The methodological quality of three foundational law enforcement drug influence evaluation validation studies, supra. Kane analyzed the three validation studies most commonly cited in American criminal prosecutions to quantify the accuracy of current US law-enforcement DRE practice: Bigelow, Bickel, Roache, Liebson, and Nowowieski, Identifying Types of Drug Intoxication: Laboratory Evaluation of the Subject Examination Procedure, DOT HS 806-753 (NHTSA 1985) (the Johns Hopkins study); Compton, Field Evaluation of the Los Angeles Police Department Drug Detection Program, DOT HS 807 012 (NHTSA 1986) (the LAPD 173 study); and Adler and Burns, Drug Recognition Expert (DRE) Validation Study (Arizona Governor's Office of Highway Safety 1994).
Kane's analysis applied the QUADAS (Quality Assessment of Diagnostic Accuracy Studies) framework, which is the standard tool for evaluating the methodological quality of diagnostic-accuracy research in evidence-based medicine. His core conclusions were that the three validation studies did no reference testing of driving performance or physical or mental impairment; that they investigated tests different from those currently employed by US law enforcement; that they used methodologies that biased the reported accuracies; and that they reported DRE accuracy statistics that are not externally valid.
The methodological problems Kane identified include selection bias (subjects pre-screened in ways that did not match field conditions), forensic selection bias, spectrum bias, misclassification bias, verification bias (toxicology testing performed only on subjects who failed the DRE evaluation, so true-negative and false-negative rates could not be calculated), differential verification bias, incorporation bias, and review bias. The widely cited Compton 94-percent-accuracy figure is, on Kane's analysis, an artifact of selection bias combined with prevalence-dependent statistics: the 173-subject sample consisted not of drivers on the road but of drivers already arrested for driving impaired by what non-DRE officers recognized to be drugs. Once the sample group was selected in this way, 94 percent of the sample had drugs on board; the DRE officers then opined that every driver they tested had drugs present, and were correct 94 percent of the time because 94 percent of the sample had drugs. Kane observes that on the same sample, had officers abandoned the DRE protocol and predicted impairment at random—by flipping a coin—they would have achieved the same 94-percent accuracy.
The widely cited Adler 83.5-percent figure, similarly, is calculated by discarding mistaken DRE opinions: a single DRE encounter that produced one correct prediction and two wrong predictions was tallied not as one correct and two wrong, but only as one correct prediction, with the wrong opinions disappearing from the calculation. Kane terms this approach the "Mulligan accuracy" calculation.
The peer-reviewed externally valid statistics necessary to assess any diagnostic test's accuracy—sensitivity, specificity, and likelihood ratio—cannot be calculated from the Bigelow, Compton, or Adler data, for the structural reasons Kane describes. The faux sensitivities that can be calculated from the available numbers represent only upper bounds; the true numbers are unknown but certainly smaller. Kane's conclusion is that these validation studies do not validate current DIE practice.
The peer-reviewed literature on more recent DRE-related research is similarly critical. Hartman, Richman, Hayes, and Huestis, Drug Recognition Expert (DRE) Examination Characteristics of Cannabis Impairment, 92 Accident Analysis & Prevention 219 (2016); Logan, Kacinko, and Beirness, An Evaluation of Data from Drivers Arrested for Driving Under the Influence in Relation to Per Se Limits for Cannabis (AAA Foundation 2016); Heishman, Laboratory Validation Study of Drug Evaluation and Classification Program: Ethanol, Cocaine, and Marijuana, Journal of Analytical Toxicology (1996); Heishman, Laboratory Validation Study of Drug Evaluation and Classification Program: Alprazolam, d-Amphetamine, Codeine, and Marijuana, Journal of Analytical Toxicology (1998); Porath-Waller and Beirness, Simplifying the Process for Identifying Drug Combinations by Drug Recognition Experts, 11 Traffic Injury Prevention 453 (2010); and Porath-Waller, Beirness, and Beasley, Toward a More Parsimonious Approach to Drug Recognition Expert Evaluations, 10 Traffic Injury Prevention 513 (2009), each address particular aspects of DRE-protocol performance and identify substantial limitations on the protocol's reliability when applied to specific drug categories.
Cannabis Pharmacokinetics and the Per Se Problem
Even if the DRE protocol could reliably identify a person who is impaired, and even if it could reliably attribute that impairment to cannabis as opposed to alcohol, fatigue, anxiety, or some other cause, a fundamental scientific problem remains: there is no peer-reviewed dose-response relationship between THC concentration in blood or oral fluid and driving impairment. Setting an above-zero per se THC threshold therefore lacks scientific justification.
The Michigan Impaired Driving Safety Commission's 2019 report cited above documented that the elimination of delta-9 THC undergoes a very rapid initial elimination over several hours, with a half-life of approximately six minutes, followed by a long terminal elimination phase with a half-life of approximately 22 hours or more. The Commission also documented that regular users of cannabis respond differently to the same dose of delta-9 THC than occasional or infrequent users due to the phenomenon of tolerance, and that the relationship between blood THC and impairment is therefore poor.
The peer-reviewed literature is consistent. Marilyn A. Huestis, who served as Chief of Chemistry and Drug Metabolism at the U.S. National Institute on Drug Abuse (NIDA) until her retirement in 2016, has repeatedly documented that THC blood levels correlate poorly with impairment, a position that the National Highway Traffic Safety Administration adopted in its 2017 Report to Congress when it warned that setting legal per se limits for THC is scientifically unjustified. White and Burns, How to Read a Paper on the Short-Term Impairing Effects of Cannabis: A Selective and Critical Review of the Literature, 8 Drug Science, Policy and Law (2022), reviewed all of the recent cannabis-and-driving studies and found that experienced marijuana smokers are rarely impaired to a measurable degree. White and Burns concluded that approximately half of apprehended THC-positive drivers are unimpaired, with upwards of 90 percent being unimpaired on certain measures.
Arkell and colleagues, in an Australian simulator study cited in the White and Burns review, documented examples of subjects who were completely unimpaired at THC concentrations approximately 500 times the typical zero-tolerance per se limit, and at approximately 800 times that limit. Wurz and DeGregorio, Indeterminacy of Cannabis Impairment and Delta-9-Tetrahydrocannabinol (Delta-9-THC) Levels in Blood and Breath, 12 Scientific Reports 8323 (2022), reached the same conclusion—that there is no clear relationship between specific blood or oral fluid concentrations of THC and impairment, and that there is therefore no scientific justification for the use of per se legal limits for THC blood concentrations. McCartney, et al., Are blood and oral fluid Δ9-tetrahydrocannabinol (THC) and metabolite concentrations related to impairment?, in a 2021 review focused specifically on biomarker-performance relationships, found no such relationships for regular users of cannabis and only very weak relationships for occasional users.
Pearlson, Stevens, and D'Souza, in their broader 2021 review Cannabis and Driving, advised that while legislators may wish for data showing straightforward relationships between blood THC levels and driving impairment paralleling those of alcohol, the widely different pharmacokinetic properties of the two substances make this goal unrealistic.
The 2023 JAMA Psychiatry Randomized Clinical Trial
The most significant recent peer-reviewed evaluation of the field sobriety tests as applied to cannabis is Marcotte, Umlauf, Grelotti, Sones, Mastropietro, Suhandynata, Huestis, Grant, and Fitzgerald, Evaluation of Field Sobriety Tests for Identifying Drivers Under the Influence of Cannabis: A Randomized Clinical Trial, 80 JAMA Psychiatry 914 (September 2023). This was a double-blind, placebo-controlled, parallel randomized clinical trial conducted from February 2017 through June 2019 at the Center for Medicinal Cannabis Research at the University of California, San Diego, with data analyzed from August 2021 through April 2023. Participants were aged 21 to 55, had used cannabis in the past month, and were randomized 1:1:1 to placebo (0.02 percent THC), 5.9 percent THC cannabis, or 13.4 percent THC cannabis, smoked ad libitum.
The principal results of the Marcotte study, as reported at 80 JAMA Psychiatry 916 to 922, are that officers classified 98 of 121 participants in the THC group (81.0 percent) and 31 of 63 participants in the placebo group (49.2 percent) as field-sobriety-test impaired at the first evaluation, 70 minutes after smoking. Of the 128 participants classified as FST impaired, officers suspected 127 (99.2 percent) had received THC.
The most defense-relevant findings are that during the first attempt at performing the walk-and-turn and the one-leg stand, completely sober subjects—subjects whose sobriety was confirmed through urine and oral-fluid testing—frequently failed these tests at the same rate or even greater rates than THC dosed subjects: approximately 83.3 percent of completely sober subjects failed the walk-and-turn; approximately 58.6 percent of completely sober subjects failed the one-leg stand; and approximately 50 percent of completely sober subjects failed both the walk-and-turn and the one-leg stand. The Marcotte study noted that the placebo group did not complete a median of 8 (interquartile range, 5 to 11) of 27 individual FST components as instructed, even though the field sobriety tests were administered by certified DRE instructors—the highest training level for impaired-driving detection.
Marcotte and colleagues concluded that although the FSTs differentiated between THC- and placebo-exposed participants, the substantial overlap of FST impairment between groups, and the high frequency at which FST impairment was suspected to be due to THC, suggest that absent other indicators, FSTs alone may be insufficient to identify THC-specific driving impairment. The high rate at which sober subjects failed the standardized tests carries direct implications for the reliability of any drunk or drugged-driving prosecution that rests, as most do, on the SFST battery as the foundational evidence of impairment.
Step-by-Step Critique of the DRE Protocol
The MIAOWIA and Michigan Medical Marihuana Association amicus curiae brief in Bowden developed a step-by-step critique of the twelve-step DRE protocol. The same critique applies to DRE-based testimony in any drug category, not solely cannabis.
Step One: Breath alcohol test. The breath test is intended to rule out alcohol as the cause of impairment, but as the analysis on the Breath Testing Expert Witness Services subpage discusses in detail, breath testing carries its own substantial uncertainty, and a low-but-positive breath alcohol result does not necessarily exclude alcohol as a contributing factor.
Step Two: Interview of the arresting officer. This step introduces confirmation bias: the DRE officer enters the evaluation already informed of what the arresting officer suspected.
Step Three: Preliminary examination and first pulse. NHTSA's training instructs the officer at this step to make a preliminary assessment of whether nystagmus is present in the subject's eyes and to make an initial estimation of the angle of onset, on the theory that the angle may help to determine whether the subject has consumed some drug other than alcohol. This contradicts the holding of People v Berger, 217 Mich App 213 (1996), which limits HGN admissibility to the presence of alcohol, and there is no Michigan case law that supports HGN as an acceptable method to identify substances other than alcohol.
Step Four: Eye examination. The eye examination includes horizontal gaze nystagmus, vertical gaze nystagmus (VGN), and the lack of convergence test. The HGN issues are addressed in detail on the HGN Expert Witness Services subpage. VGN has never been validated as a clue in any of the four NHTSA validation studies, and lack of convergence is not a recognized clinical sign of drug impairment in the peer-reviewed neuro-ophthalmology literature.
Step Five: Divided-attention psychophysical tests. The DRE protocol incorporates the SFST battery, and adds the Modified Romberg Balance and the finger-to-nose test. The validity issues with the SFST battery as applied to alcohol are addressed on the SFST Expert Witness Services subpage; those issues are compounded when the battery is used to identify drug impairment that the battery was never validated to detect. Black, Wall, Rockette, and Kitch, Normal Subject Postural Sway During the Romberg Test, 3 American Journal of Otolaryngology 309 (1982), documented that postural sway in healthy subjects is wide-ranging, and the Modified Romberg has not been validated as a diagnostic tool for drug impairment in the peer-reviewed literature.
Step Six: Vital signs. The DRE protocol assigns presumptive significance to elevated or depressed blood pressure, pulse, and temperature in particular drug categories. Mayo Clinic and MedlinePlus reference materials document that normal vital-sign ranges are wide and that anxiety produced by an arrest will, by itself, often elevate pulse and blood pressure into ranges that the DRE protocol categorizes as indicative of stimulant use.
Step Seven: Darkroom and pupillometer examination. The DRE officer takes the subject to a darkroom and uses a pupillometer (a paper card with circles ranging from 1.0 mm to 10.5 mm in 0.5 mm increments) to estimate pupil size under three lighting conditions. This step purports to apply medical clinical assessment without the equipment, lighting calibration, or training of an ophthalmologist or optometrist.
Steps Eight through Eleven: Muscle tone, injection sites, statements, and DRE opinion. Steps eight through eleven culminate in the officer's subjective opinion as to the category of drug responsible. As the Court of Appeals observed in Bowden, this opinion is ultimately based on the DRE officer's subjective judgment, and the ability of an officer to make such a judgment based on the application of the DRE protocol has not been tested to demonstrate accuracy and validity.
Step Twelve: Toxicological examination. The toxicology screen identifies the presence of drugs and metabolites in blood or urine. The presence of a drug in toxicology does not establish impairment, particularly for cannabis, where THC and its metabolites can be detected for hours, days, or weeks after the impairing effect has dissipated.
Categories of Defense Analysis in Michigan Drugged-Driving Cases
The categories of analytical work that I most commonly perform in Michigan drugged-driving engagements are the following.
Pre-arrest investigation review. The officer's roadside investigation must establish probable cause to arrest; under the Michigan Supreme Court's decision in People v Armstrong (2025), the smell of marijuana, by itself, no longer suffices. The investigation must include articulable observations of impaired driving conduct or other indicia of intoxication. The SFST battery, when administered, must comply with the NHTSA-prescribed protocol; the failures cataloged on the SFST subpage are, in drugged-driving cases, compounded by the protocol's lack of validation for non-alcohol impairment.
DRE protocol audit. Where a DRE evaluation has been conducted, I review each of the twelve steps for compliance with the IACP/NHTSA training, identify confirmation-bias signals (such as the arresting officer's brief at step two), evaluate the reasonableness of the DRE officer's vital-sign and pupil-size interpretations against the published normal ranges, and document each step at which the protocol's stated purposes are not in fact achieved.
Toxicology review. I review the chain of custody, the validation of the analytical methods used, the sensitivity and specificity of the assays, the metabolite-versus-parent-drug profile, and the temporal relationship between drug ingestion, blood draw, and alleged impairment.
Pharmacokinetic and pharmacodynamic analysis. The peer-reviewed literature on cannabis (Huestis, White and Burns, Wurz and DeGregorio, McCartney, Pearlson, Arkell), benzodiazepines, opioids, and prescription stimulants establishes the dose-response and time-course relationships that the prosecution will not address in its case-in-chief. I tailor my analysis to the specific substance(s) at issue and to the peer-reviewed literature applicable to that substance.
Daubert/MRE 702 motion preparation. Following Bowden, defense counsel in marijuana cases should consider filing a pretrial motion to exclude DRE testimony under MRE 702 and Gilbert. I prepare expert reports that address the scientific reliability foundation, identify the categorically inadequate validation studies, and provide the trial court with the peer-reviewed and authoritative-publication record (Kane, NHTSA's 2017 Report to Congress, the Michigan Impaired Driving Safety Commission's 2019 Report, and the 2023 JAMA Psychiatry trial) that supports exclusion under Bowden.
My Training and Lecture Record on Drugged Driving
I have lectured on drugged-driving issues since 2013, including The ABC's of Drugged Driving for the Criminal Defense Attorneys of Michigan (CDAM) in 2020, and continuing-education programs at the Michigan Association of OWI Attorneys (MIAOWIA) Board of Directors, on which I have served since 2023. I served as President of CDAM from 2014 through 2015, during which the Michigan Medical Marihuana Act framework was undergoing significant litigation, and I have been a member of the National College for DUI Defense (NCDD) since 2004 and of the DUI Defense Lawyers Association (DUIDLA) since 2021.
I have completed Advanced Roadside Impaired Driving Enforcement (ARIDE) training at the NHTSA/IACP level in 2017, which is the intermediate course between the SFST Practitioner certification and the full DRE School and which addresses drug-recognition issues for general patrol officers. I have studied the IACP DRE Student Manual and the 2018 IACP Drug Recognition Expert Course, Instructor Guide in addition to the underlying validation studies and the peer-reviewed critiques. I have read and applied the Kane's paper, the Hartman (2016) Accident Analysis & Prevention paper, the Logan, Kacinko, and Beirness (2016) AAA Foundation report, the Heishman (1996, 1998) Journal of Analytical Toxicology papers, the Porath-Waller and Beirness (2009, 2010) Traffic Injury Prevention papers, the Marcotte (2023) JAMA Psychiatry trial, the White and Burns (2022) Drug Science, Policy and Law review, the Wurz and DeGregorio (2022) Scientific Reports paper, and the Black (1982) American Journal of Otolaryngology Modified Romberg study.
From 2021 through 2024, I served as an Adjunct Professor of Forensic Science at Madonna University, where I taught FOR 4650 Ethics & Expert Testimony and FOR/CJ 5230 Criminal Law and the Rules of Evidence. The course content addressed, in substantial part, the Daubert/Gilbert framework as applied to the kinds of forensic testimony at issue in drugged-driving prosecutions.
Scope of Engagement
A typical drugged-driving expert engagement begins with my review of the police narrative report; the in-car and body-worn camera video covering the entire stop, investigation, and arrest sequence; the officer's SFST data sheet; the DRE evaluation form, narrative, and any rolling notes, where a DRE evaluation was conducted; the officer's training records, including the SFST Practitioner certification, the ARIDE certificate, and any DRE certification and recertification documentation; the breath alcohol test record, where one was administered; the toxicology report, including the underlying chromatographic data where available; the chain-of-custody documentation; and any contemporaneous medical, prescription, or physiological information that bears on alternative explanations for the observations relied on by the officer.
I then prepare a written expert report that identifies, on a step-by-step basis, every departure from the applicable training protocol; every confirmation-bias signal in the officer's narrative; every clinical observation that is more reasonably explained by anxiety, fatigue, prescription medication, or a medical condition than by recent drug use; every analytical and chain-of-custody issue in the toxicology; and every aspect of the case in which People v Bowden, NHTSA's 2017 Report to Congress, the Michigan Impaired Driving Safety Commission's 2019 Report, the Kane (2013) peer-reviewed critique, the Marcotte (2023) JAMA Psychiatry trial, or the broader peer-reviewed cannabis literature (Huestis, White and Burns, Wurz and DeGregorio, McCartney, Pearlson, Arkell) bears on the reliability of the prosecution's evidence. The report relates each identified issue to the underlying primary scientific literature and explains, in language accessible to the trier of fact, why the inference of drug-induced impairment is not sustained on the record presented.
Retention
I accept drugged-driving expert witness engagements from defense attorneys throughout Michigan and, on a case-by-case basis, in neighboring jurisdictions. Inquiries may be directed to Maze Legal PLC, 37211 Goddard Road, Romulus, Michigan 48174, or by telephone at (734) 941-8800.
