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Standardized Field Sobriety Tests (SFSTs) are Junk Science!

Mimi Coffey is a Texas DWI lawyer who fights! She not only fights in the courtroom, for decades she has been waging a war on the junk science, known as DWI standardized field sobriety tests, used to wrongly convict people. She is recognized nationwide for her efforts. Mimi knows that police use this junk science to justify their DWI arrests, and wants to help you fight back. To find the best way to fight back, Mimi conducts a full case evaluation. During this evaluation, Mimi will get to know you and your story before going over all the evidence with you to discuss the strongest points of your case.

DWI Standardized field sobriety tests (SFSTs) are the “tests” that police officers use when investigating someone for a DWI. These tests were developed by a psychologist under federal grant funding, Dr. Marcelline Burns. She admits that the tests have no correlation with one’s ability to operate a motor vehicle.  The underlying studies have received much criticism due to the lack of adherence to scientific peer review protocols. Dr. Spurgeon Cole conducted landmark research that exposed the deficiencies of these tests for determining alcohol intoxication Unfortunately, police falsely convict a large number of people due to these tests. The three standard tests are:

  • Horizontal Gaze Nystagmus (HGN), also known as the “eye test”;
  • Walk-and-turn (W&T), sometimes called the “walk in a line” test; and
  • One Leg Stand (OLS)

SFST “Validation” Studies

The SFSTs are not validated on driving ability. Mimi wrote a thoroughly researched paper on the deficiencies of the field sobriety tests.  It was published for lawyers nationwide in The Champion (link for lawyers). The Wisconsin Court of Appeals referenced Mimi’s paper in one of their decisions, holding that SFST evidence is admissible as relevant, but can be attacked for reliability. Other lawyers across the country have referenced this work. It succinctly tears apart the problems with the tests in terms of lack of science. The SFST course for officers (the police DWI manual) focuses on the proper administration of these tests. The issue is that these tests lack the foundation necessary to be used in the manner of which they are being used for arrest decisions and testimony for convictions in court. The responsibility lies with the National Highway Traffic Safety Administration (NHTSA).

Most unfortunately, the science has been sacrificed for the politics of law enforcement. A goal to lessen DWI deaths must not sacrifice truth and science. The marriage of the International Association of Chiefs of Police and NHTSA is dangerous to the integrity of the judicial process. Politics must never trump science. In addition to Dr. Spurgeon Cole’s study, there are others that address the serious deficiencies of a police driven agenda when it comes to science. Dr. Steven Rubenzer has also written critically about its shortcoming.

Mimi’s article is the most comprehensive in addressing the foundational deficiencies of these tests.  Some brief introductory key points regarding the NHTSA studies are:

1977 SFST Validation Study

The biggest issue with this study is that, aside from being the first major study (and thus “setting the bar” for the other studies), researchers conducted the tests in a controlled environment rather than in actual practice. In other words, researchers conducted the tests in a “laboratory”, rather than on roadside after a traffic stop. The study claims that in actual practice officers would decide to release, rather than arrest, if the officer was uncertain, but since this is the first major test, the researchers did not provide a basis for this statement.

Other problems involved subjects arriving already under the influence, which was ignored by the researchers despite the instructions for the experiment, and the sheer number of tests performed, since the three-test battery had not yet been completely “validated” at the time.

1981 Study

This is the study that “validated” and “standardized” the three-test battery of HGN, W&T, and OLS. One problem is that the researchers did not test subjects for other drugs, despite the researchers wanting to limit the study to only alcohol impairment. This casts a shadow over the study because there was no way to determine if other substances affected the observations.

1983 Study

This study is particularly problematic because took only three months to perform and researchers could not monitor all police data collection. In other words, the researchers merely compiled the limited date they received (but did not monitor). Another major problem is that all but one of the agencies analyzed equipped officers with PBTs (portable breathalyzers, basically). The mere presence of PBTs interferes with the researcher’s stated purpose of only using the SFSTs to make arrest decisions. The study even says that some arrest decisions could be based on the PBTs! Furthermore, since this study involved real drivers subject to actual arrest, police already suspected many subjects of DWI before the officer conducted the SFSTs (based on driving behavior, for example). Officers incorrectly classified and falsely arrested at least 16% (~197) of drivers.

Colorado Study

This study differs from the earlier studies in that the study included weather conditions and that the study was based on Colorado’s lower .05 limit. Researchers only observed 41% of investigations. But, the observers were all associated with law enforcement in some way. In other words, not only were less than half of the investigations observed, the observed investigations did not have “neutral” observers! Because this study focused on the .05 BAC limit, it did not (and should not) validate any tests used to determine BACs of .08 or above.

San Diego Study

This study found HGN to be the most effective test and that the addition of the W&T and OLS did not raise the probability of determining BAC significantly. The study also says that HGN lacks “face validity” because it has no link to driving. In addition, the study admits that officers cannot accurately measure “complex human performance” such as driving skills  at roadside. Finally, the study states that the link between BAC and driving is a separate issue.

An additional issue is that this study involved officers with significant SFST experience, which means that it did not determine whether a fairly new officer would make correct arrest decisions.

Florida Study

The flaw in this study is, out of the 379 subjects, only 256 made it to the final report. Even then, no observation existed for about 38% of the 379 tests performed. The test is also interesting because it shows that failure to arrest impaired drivers included subjects who passed the W&T and OLS but displayed 4 clues on HGN.

Texas DWI, Mimi Coffey DWI Lawyer, SFSTsFalse positives based on Junk Science

Back in 1997, when the legal limit was .10 instead of .08, Dr. James Booker, a Ph.D in Chemistry, calculated how many people failed the Standardized Field Sobriety Tests even when below the legal limit. This study, as seen in the image above, analyzed 80 tests. 45 of the tests showed BAC of .15 or more, and 35 showed between .00 and .149. Of those 35, 20 of the tests showed BAC of above .10, and 15 tests showed below the legal limit. In each of the 35 tests between .00 and .149, officers made arrests based on reasonable suspicion and/or probable cause of alcohol impairment. The offices made incorrect arrests in 15 case, which is 43%! That means that officers can make incorrect arrest decisions almost half of the time based on these standardized field sobriety tests!


  • Mimi Coffey is Board Certified in DWI by the NCDD. She is a fighter for all.  For those looking for a “DWI lawyer near me”, know that she handles most all of North Texas*. Courts in the city of arrest do no handle DWIs. County courts handle DWI cases. She has been practicing law in north Texas for 25 years.  She is well known as a top criminal lawyer for DWI in particular.
  • *DWI lawyer Ft. Worth, DWI lawyer Dallas, DWI lawyer Arlington, DWI lawyer Weatherford, DWI lawyer McKinney, DWI lawyer Plano, DWI lawyer North Richland Hills, DWI lawyer Grapevine, DWI lawyer Southlake, DWI lawyer Euless, DWI lawyer Bedford, DWI lawyer Grand Prairie, DWI lawyer Azle, DWI lawyer Mansfield, DWI lawyer Frisco, DWI lawyer Allen, DWI lawyer Burleson, DWI lawyer Cleburne, DWI lawyer Decatur, DWI lawyer Rhome, DWI lawyer Denton, DWI lawyer Argyle. . .   Please note this is a partial listing. Mimi handles cases of out of the following counties: Tarrant, Parker, Johnson, Wise, Dallas, Denton, Colllin, Ellis, Kaufman, Hood

Defending Asleep-at-the-Wheel Cases

Defending Asleep-at-the-Wheel Cases

Mimi Coffey DWI Lawyer, Texas DWI

By Mimi Coffey

Ethanol is a central nervous system depressant. As one ingests more, the body is subject to more central nervous system depressant effects up to and including death. One of the well-known side effects of the ingestion of alcohol is sleepiness. However, an issue in a DWI case is the ability to scientifically distinguish between sleep deprivation and intoxication. Sleep deprivation brings about changes in physical and cognitive behaviors which are very similar to alcohol impairment including disorientation, slurred speech, and the inability to control the body and perform simple tasks.[1] Although they are frequently used interchangeably, the terms fatigue and sleepiness are vastly different. One study makes the distinctions:

Fatigue is a more complex phenomenon that may be defined as the decreased capability of doing physical or mental work, or the subjective state in which one can no longer perform a task effectively.[2] Sleepiness has a more specific meaning than fatigue, relating to reduced alertness as a result of increased pressure to fall asleep… It is associated with decrements in

vigilance, reaction time, memory, psychomotor coordination, information processing, and decision making.[3]

Studies have shown that a sleep deprived individual can exhibit a lack of coordination, memory impairment, personality change, irritability, blurring of vision, unsteadiness and transient confusion.[4] Additionally, the emotions of a sleep deprived person can be negatively affected. A strong relationship has been found between sleep and the intensity of manic symptoms. [5] A study on male teenagers has proven a correlation between sleep deficiency and aggression[6]. Extensive lack of sleep (over a few days) has shown decreased emotional intelligence, deteriorated interpersonal skills, enhanced esoteric thinking and a tendency to become superstitious, as well as intense frustration and aggression.[7] An area of concern arises in the context of sleep deprivation prevalence, which exists even separate and distinct from alcohol use. It is estimated that 30-50% of all adults suffer from some form of sleep deprivation, which affects their thinking, ability to process information, and reaction time.[8]

In discerning the impact of sleep deprivation, it is important to understand that this phenomenon is not related to the last 24 hours of one’s day. It has been shown that getting six hours of sleep for ten days straight is the equivalent of a sleep deprived person who has not slept in 24 hours[9]. The key for the attorney is to delve deep into the facts and determine whether sleep deprivation issues are relevant and to what degree. Fatigue of 20-25 hours of sleeplessness impairs task performance comparable to a .10 alcohol concentration.[10] Another study focused on time of day and the body’s circadian rhythm revealing that between 10:00 pm and midnight, deficits from sleep equivocated to a BAC of .05%[11]

The Horizontal Gaze Nystagmus test has been proven to be very problematic according to the 2007 National Highway Traffic Safety Administration’s Robustness of The Horizontal Gaze Nystagmus Test Study. Their own data proves false positives for those not .08 or more. Dr. Karl Citek, an often-referenced government advocate of the HGN, testified under oath in a Daubert hearing of In re Seiler on February 13, 2014 that 50-60 % of normal sober individuals will exhibit end point nystagmus (HGN at maximum deviation).[12] He concedes that he has seen individuals demonstrate all six clues, as well as vertical, while under the .08 limit.[13] In that same hearing he testified that, in the study he conducted in 2011 involving sleep deprivation of at least 24 hours, there were no effects on the field sobriety tests[14]. One must carefully analyze this study and its source. He is referring to his Sleep Deprivation Does Not Mimic Alcohol Intoxication on Field Sobriety Testing study which had representatives of the Oregon State Police and Washington County (Oregon) Sheriff’s Office as two of its authors.

On the first page of his study, Citek concedes that “SD (sleep deprivation) has been shown to affect saccadic eye movements (the jerking looked for in the HGN). [15] His graph of endpoint nystagmus (HGN at maximum deviation) shows nearly 90% of sleep deprived individuals displaying these clues with less than .04 alcohol[16]. The study is flawed as only 1 out of 29 test subjects was over 34 years old (not representative of the DWI population) and none of the tests were conducted during typical DWI arrest times (past midnight into early morning where the one’s circadian rhythm is disrupted). Yet despite such a biased study, Citek’s statistical analysis showed that the One-Leg Stand count (cognitive reasoning) decreased with sleep deprivation.[17] Outside the HGN test, police officers frequently use “bloodshot eyes” to describe an intoxicated person. Yet this is a very common physical sign of fatigue. As a matter of fact, in Jack Stuster’s U.S. Department of Transportation, NHTSA Final Report, The Detection of DWI at BACs Below 0.10 (Sept. 1997), the NHTSA took the position:

“Finally, some cues were eliminated because they might be indicators more of social class than of alcohol impairment. … a flushed or red face and bloodshot eyes are open to subjective interpretation and could be due to allergies or caused by outdoor work.”[18]

One very good clue that an individual is sleep deprived as opposed to intoxicated would be the physical presence of bags under one’s eyes.

The existence of sleep deprivation in automobile crashes is all too common. One British study found that alcohol (in amounts equal to .08) produced impairment across the whole drive with respect to simulated steering performance, while on average the sleep deprivation subjects showed normal steering at the start of the drive with progressive deterioration.[19] As a result, it is very important that the defense lawyer closely dissect the driving at hand. Were there 911 calls at the start of the drive? If so, over what distances? Crashes are part and parcel to sleep deprivation as well as intoxication. A 2008 National Sleep Foundation survey found that more than 36% of participants reported falling asleep while driving at least once in the past year.[20] As a matter of fact, “drowsiness is the primary causal factor in 100,000 police-reported crashes each year, resulting in 76,000 injuries and 1,500 deaths.”[21]

The time of crashes also relates to the body’s circadian rhythm. Findings in one study show that the major time of crashes occurs during the night with a secondary peak at siesta time (3 pm).[22] It is worth noting that in New Mexico, there was an increase in the number and proportion of alcohol-related traffic crashes following the seven days after the change to and from daylight savings.[23] Even one of the founders of NHTSA’s standardized field sobriety testing program, H. Moskowitz, has conceded, “[c]onsidering that the majority of alcohol-related accidents occur at night, there is a need for increased examination on the role of fatigue, circadian cycles, and sleep loss.”[24] There is also a strong correlation between sleep apnea and the risk of having a traffic accident[25]

The bottom line is that lack of sleep produces many of the same effects associated with being drunk, including lack of coordination, judgment and reaction time. [26] It has been found that sleep of five hours a night for four consecutive days impairs performance to such a degree that traffic safety is affected. [27] With sleep deprivation becoming a highly researched topic and an area of concern for the NHTSA, it will come as no surprise if there is future a push for laws that directly criminalize sleep deprivation and traffic accidents. The complications will be in proof of sleep deprivation in individual cases, not the underlying problems which cause accidents. Regardless, the issues and rehabilitative concerns for addressing intoxication versus sleep deprivation are different in nature. It is the responsibility of the criminal defense attorney to familiarize one’s self with the sleeping patterns of every DWI case to see the applicability of such a defense.

The body of research out there exists mainly in the medical field. The characteristics of sleep deprivation and intoxication have been proven to overlap. It is not fair to allow a prosecutor, judge or jury to dismiss considerations of sleep deprivation where such considerations are relevant, and sometimes necessary, to one’s case. The field is a vast one, which involves considerations of individuals’ medical issues (is sleep apnea at play or other physical ailment which cause lack of sleep?), employment (is there shift work or sleep loss due to multiple jobs?), and unique sleep patterns at the time of the DWI occurrence (sleep deprivation effects can accumulate over days as reference above, not just a single 24-hour instance). Consulting experts may—and possibly should—include the relevant fact witnesses, such as one’s sleep disorder doctor or primary physician, in addition to sleep experts who are both published and in practice (both therapeutic and medical doctors). Finding the right solution for the sleep deprived DWI client should also involve counseling them to find healthy alternatives and medical solutions that can alleviate their sleep loss and prevent future occurrences.


[1] Carolyn Schur, DUI and the Effect of Sleepiness, 2 Counterpoint Journal (Aug. 7, 2019), https://www.counterpoint-journal.com/vol-2-iss-2-art-6—sleepiness.html.

[2] James M. Lyznicki, Sleepiness, Driving, and Motor Vehicle Crashes, 279 JAMA 1908, 1909 nn.14-15 (1998).

[3] Id. nn.11, 13.

[4] Michael E. Reid, Fatigue, 42 Mo. DUI Handbook § 5:3 n.18 (2017).

[5] Jolanta Orzel-Gryglewska, Consequences of Sleep Deprivation, 23 Int’l J. Occupational Med. and Envtl. Health 95, 97 n.17 (2010).

[6] Id. at 104.

[7] Id. at 104 nn.119-20.

[8] Reid, supra note 4, n.15.

[9] Clayton Kerbs, The Importance of Sleep, 87-APR J. Kan. B.A. 15, 16 n.8 (2018).

[10] Orzel-Gryglewska, supra note 5, at 107.

[11]A.M. Williamson, Moderate sleep deprivation produces impairments in cognitive and motor performance equivalent to legally prescribed levels of alcohol intoxication, 57 Occup. Environ. Med. 649, 654 nn.15-16 (2000).

[12] In re Seiler, page 21 (2014) (Transcript of Daubert Hearing: Karl Citek).

[13] Id. at 31.

[14] Id. at 4.

[15] Karl Citek, Sleep Deprivation Does Not Mimic Alcohol Intoxication on Field Sobriety Testing, 5 J. Fors. Sci. 1170 nn.41-42 (2011).

[16] Id. at 1176.

[17] Id. at 1173.

[18] Jack Stuster, The Detection of DWI at BACs Below 0.10, US Department of Transportation, page 14 (1997).

[19] M.A. Hack, Comparison of the effects of sleep deprivation, alcohol and obstructive sleep apnoea (OSA) on simulated steering performance, 95 Respiratory Med. 594, 600 (2001).

[20] George W. Ingham, Another Drink, Another Hour: Using Dram Shop Liability to Determine Employer Liability for Injuries Caused by Fatigued Commuting Employees, 17 Geo. Mason L. Rev. 565 n.3 (2010).

[21] Id. n.4.

[22] Allan I. Pack, Characteristics of Crashes Attributed to the Driver Having Fallen Asleep, 27 Acc. Anal. and Prev. 769, 771 (1995).

[23] E.J.D. Ogden, Effects of Alcohol and Other Drugs on Driver Performance, 5 Traffic Inj. Prev. 185, 190 (2004).

[24] Id. at 185.

[25] J. Teran-Santos, The Association Between Sleep Apnoea and the Risk of Traffic Accidents, 340 New Eng. J. Med. 847 (1999).

[26] P.A. Fransson, Effects of 24-hour and 36-hour sleep deprivation on smooth pursuit and saccadic eye movements, 18 J. Vestibular Res. 209 (2008).

[27] David Elmenhorst, Performance impairment during four days partial sleep deprivation compared with the acute effects of alcohol and hypoxia, 10 Sleep Med. 189 (2009).

More about Mimi Coffey

When people look for a Top DWI Attorney or Best DWI Attorney, they look for experience, certification, and respect in the legal community. Mimi Coffey is a nationally-renowned trial attorney, board-certified in DWI by the NCDD. She has been practicing for over 24 years and is an author of multiple DWI Defense textbooks. She is also a national and state-wide lecturer on the law.

The Coffey Firm handles a wide variety of cases, including Unlawful Carrying Weapon (UCW), Assault (including family violence), Theft and Possession charges.

Mimi is also listed on several “top” directory listings such as DWI Lawyers for Wise County, DWI Lawyer Tarrant CountyDWI Lawyer Dallas County, DWI Lawyer Collin County and DWI Lawyer Parker County. Mimi is a caring DWI Lawyer in DFW, She is also involved in the Texas Tech School of Law foundation and enjoys using the skills she has developed to give back to the community.