The Journal of The DuPage County Bar Association

Back Issues > Vol. 14 (2001-02)

Field Sobriety Testing In Illinois - Science V. Law
By Donald J. Ramsell

In People v. Bostelman (2d Dist. 2001) 2-00-0850, the Second District Appellate Court was called upon to decide whether field sobriety tests were admissible in the absence of evidence that the tests were generally acceptable under scientific principles or in the particular field in which they belong, as recognized by Frye v. United States, 293 F. 1013, 1014 (D.C. Cir. 1923).

The Bostelman court, in holding that field sobriety tests need not comply with Frye, stated that the field sobriety tests "measured abilities that are tested innumerable times throughout the average day of the normally active person," and therefore are not subject to attack under Frye principles. 

The fundamental problem in the Bostelman decision is that it implicitly holds that police officers may create any number of physical or mental "exercises" and then refer to them as "sobriety tests." In fact, two of the "tests" given by the officer in Bostelman, namely the alphabet test and count backwards test, have never been validated as reliable indicators of intoxication. The three remaining tests in Bostelman, i.e., the One-Leg Stand test, the Walk-and-Turn test, and the Horizontal Gaze Nystagmus test have only been validated as reliable indicators of intoxication when they are properly administered and properly scored in strict compliance with National Highway Traffic Safety Administration (NHTSA) standards. According to NHTSA, the failure of an officer to comply with proper administration and scoring compromises the validity of these tests entirely. NHTSA "DWI Detention and Standardized Field Sobriety Testing Student Manual", Section VIII, 2000, AVA 20839-BBOINA, (National Technical Information Service, Washington, D.C. 2000).

In the late 1970’s, NHTSA was called upon to develop a battery of reliable standardized field sobriety tests to aid in the detection of drunk drivers. The result was the One-Leg Stand test, the Walk-and-Turn test, and the Horizontal Gaze Nystagmus test. According to NHTSA, laboratory research revealed that the One-Legged stand test was 65% accurate in identifying subjects whose blood alcohol concentrations were 0.10 or higher, the Walk-and Turn was 68% accurate, and the HGN was 77% accurate. A large scale field valuation study was then performed in 1982 and 1983.

As per NHTSA, this large scale validation study was the first significant assessment of the "workability" of the standardized field sobriety tests (SFSTs) under actual enforcement conditions, and it was the first time that completely objective clues and scoring criteria had been defined for the tests. U.S. Department of Transportation, N.H.T.S.A., US DOT HS 178 r10/95, "DWI Detection and Standardized Field Sobriety Testing, Student Manual", Section VIII Page 11 (1995).

If field sobriety tests simply "measure abilities that are tested innumerable times throughout the average day of the normally active person," as suggested by the Bostelman decision, then why is the error rate as high as the 35% reported by the NHTSA?

The problem with the Bostelman decision rests truly not with the court, but with the record on appeal upon which the court was required to rule. The Bostelman appeal centered on the defendant’s claim that his trial counsel was ineffective for not seeking to exclude, as lacking foundation, the arresting officer’s testimony concerning the field sobriety tests defendant underwent and the arresting officer’s subsequent opinion concerning defendant’s state of intoxication.

The recitation of the trial court proceedings by the Bostelman court suggests that the types of tests given and the procedures employed by the officer were virtually uncontested by his trial attorney. No evidence was introduced about the fallibility of field sobriety testing or about the manner in which these tests were administered. Had the record contained evidence gleaned from field sobriety student manuals, published scientific studies or testimony from experts on field sobriety testing, perhaps the Bostelman court would have rendered a different decision.

Two recent decisions from other jurisdictions did have adequate records on appeal with which to rule regarding the admissibility of so-called field sobriety tests; State of Ohio v. Homan 89 Ohio St. 3d 421 (2000) and U.S. v. Horn (U.S. Dist. Ct. Maryland 2002) 00-946-PWG.

In State of Ohio v. Homan, the Ohio Supreme Court held that in order for the results of a field sobriety test to serve as evidence of probable cause to arrest, the police must have administered the test in strict compliance with standardized testing procedures. The Homan court noted that "when field sobriety testing is conducted in a manner that departs from established methods and procedures, the results are inherently unreliable."

Unlike Bostelman, the Supreme Court of Ohio acknowledged that "experts in the areas of drunk driving apprehension, prosecution and defense all appear to agree that the reliability of field sobriety test results does indeed turn upon the degree to which police comply with standardized testing procedures."

Citing from the extensive study performed by the NHTSA, the Homan court stated:

"The NHTSA concluded that field sobriety tests are an effective means of detecting legal intoxication only when, the tests are administered in the prescribed, standardized manner, . . . the standardized clues are used to assess the suspect’s performance [and] . . . the standardized criteria are employed to interpret that performance."

It would seem that if, as Bostelman implicitly suggests, performing sobriety tests is simple, then an officer’s ability to administer and score the tests in a standardized manner should be equally as simple. Requiring the use of validated, standardized field sobriety testing in Illinois in order to avoid the possibility of erroneous arrests for drunk driving is a concept whose time has arrived, especially in light of the heightened penalties that have been attached to drunk driving convictions.

The Bostelman decision actually took a step backwards. Whereas prior caselaw had suggested that the officer must receive formal training in the administration of field sobriety tests (People v. Sides, 199 Ill. App. 3d 203 (1990)), the Bostelman court stated that no such training is necessary. Rather, Bostelman states that "so fundamental are such exercises of balance, coordination, and basic recognition to the activity of the average person that ‘even a layperson is competent to testify regarding a person’s intoxication from alcohol, because such observations are within the competence of all adults of normal experience,’ People v. Workman, 312 Ill. App. 3d 305, 310 (2000)."

In the Northeast Multi-Regional Training (NEMERT) Alcohol and Drugged Driver Detection Manual, used to train many of the patrol officers in the Chicagoland area, it states that:

"The recommended test battery consists of the nystagmus gaze test, the walk and turn test, and the one leg stand test. The administration and scoring of these tests have been standardized so they can be used in the way that makes them as sensitive as possible in detecting alcohol impairment. If the standardized admin-istration and scoring procedures presented in this manual are not followed, then the decision-making guidelines are no longer accurate."

The record presented to the Bostelman court left the court uninformed on the science behind SFSTs, and left it in the untenuous position of either affirming the trial court’s guilty verdict or establishing a far-reaching decision in DUI cases in Illinois in the face of a defendant who did virtually nothing to prove that the tests given to him were somehow unfair or improperly administered and scored.

As stated in Horn, "this highlights an inherent limitation in the process of judicial evaluation of the reliability and validity of any scientific or technical evidence: the court must . . . act as ‘gatekeeper’ to decide whether the evidence is reliable and admissible. The court, however, is limited in its ability to do so by the quantitative and qualitative nature of the evidence produced by the parties, whatever research the court may do, and any help it may derive from courts that have addressed the issue before it. This process unavoidably takes place on a continuum, and a court faced with the present task of deciding the admissibility of scientific evidence must exercise care to consider whether new developments or evidence require a reevaluation of the conclusions previously reached by courts that did not have the benefit of the more recent information. In short, neither science and technology may rest on past accomplishments – nor may the courts." Horn, slip op. at 12-13 n.15.

In Horn, the District Court of Maryland reviewed extensive caselaw, received a multitude of studies and medical articles, and heard testimony from a variety of experts on both sides regarding the validity and reliability of standardized field sobriety testing. After hearing, the court ruled that: 

1. The results of properly conducted SFSTs may be considered for probable cause or at trial;

2. The results of SFSTs cannot be used to prove a specific blood alcohol concentration;

3. There is a well-recognized causal connection between the ingestion of alcohol and exaggerated HG.N.;

4. A police officer trained and qualified to perform SFSTs may testify to his observations, if properly administered, but may not use value-added descriptions to characterize the subject’s performance, such as saying the subject "failed the test" or "exhibited" a certain number of "standardized clues" during the test;

5. If the government introduces evidence of nystagmus, the defendant may bring out either during cross-examination or by asking the court to take judicial notice of the fact that there are many causes of nystagmus other than alcohol ingestion; and

6. If otherwise admissible, the police officer may give lay opinion testimony that the defendant was Driving Under the Influence, but he may not bolster the testimony by reference to any scientific, technical or specialized information learned from law enforcement or traffic safety instruction. Horn, slip op. at 3-5.

In many respects, Horn follows Bostelman’s theory that a police officer may testify (just as any other layperson) that someone is under the influence of alcohol. Horn, however, makes clear that the police officer is not to be misrepresented to the jury or judge as some kind of expert, unless the government establishes that he is otherwise so qualified. Horn also recognizes the prejudice to the defendant that accompanies testimony regarding non-validated and non-standardized field sobriety testing by prohibiting non-standardized tests from being introduced into evidence.

The Horn ruling is based upon and supported by a variety of scientific and technical resources, which will be further discussed in this article.

As stated previously, the three SFSTs (HGN, One-Leg Stand, and Walk-and-Turn) were developed on behalf of the NHTSA beginning in the 1970’s. Amongst the reports discussing the development of the SFSTs is a June 1977 final laboratory study of subjects dosed to varying blood alcohol levels prepared for NHTSA by Drs. Marcelline Burns and Herbert Moskowitz entitled "Psychophysical Tests for DWI Arrests". DOT-HS-802-424 (National Technical Information Service, Washington, D.C. 1977). This is the study which found the HGN 77% accurate, the One-Leg Stand 65% accurate, and the Walk-and-Turn test 68% accurate in detecting impaired drivers.

A March 1981 final report prepared for NHTSA by Dr. Burns titled "Developments and Field Test of Psychophysical Tests for DWI Arrest" recommended the use of the present three test SFST battery. V. Tharp, M. Burns and H. Moskowitz, DOT-HS805-864 (National Technical Information Service, Washington, D.C. 1981).

In 1982, a field evaluation of the three SFSTs was begun, where battery-trained police officers recorded data on 1,506 drivers stopped for ‘suspicion of DWI,’ as well as a review of data recorded on an additional 1,000 drivers stopped for DWI in other states.

The results of that field evaluation were reported in "Field Evaluation of a Behavioral Test Battery for DWI, Research and Development," U.S. Department of Transportation, NHTSA, D.O.T. HS-806-475 (Sept. 1983 NHTSA Technical Note). This study reported that the HGN test was 82% accurate, the One-Leg Stand 78% accurate and the Walk-and-Turn 83% accurate in the detection of DWI offenders.

The authors of the 1983 report noted that there were significant reasons to be extremely cautious about the data collected and the conclusions drawn regarding the effectiveness of the field sobriety tests that were used. First, officers were not randomly assigned to different groups, so outcomes may have been affected by selection and assignment bias. Second, and most important, in the great majority of cases the drivers were given portable breath tests prior to the arrest decision, so the officers’ evaluation of the field sobriety tests may have been affected by this knowledge of the drivers’ reported alcohol concentrations prior to the arrest decision having been made.

As a result of these studies, in 1984 the NHTSA published their first field sobriety testing manual, "Improved Sobriety Testing", U.S. Department of Transportation NHTSA (1984) DOT HS-0-421-018. It stated that "if the standardized testing and scoring procedures in this Manual are not followed the decision making guidelines will not be accurate."

Amongst the important aspects noted in the 1984 NHTSA Improved Sobriety Testng Manual’s administration and scoring procedures is that the officer is told to "be sure to mention [to the suspect] that part of your evaluation will be based upon how well he follows instructions and performs exactly as demonstrated." With regard to the HGN test, officers are informed to "check yourself monthly with (a 45 degree template) to be sure that your accuracy has been sustained." The manual also notes that the onset point at a BAC of 0.10 is about 40 degrees (the 45 degree angle correlates to 0.05 BAC). For the Walk-and-Turn test, the manual notes that the instructions should be given "exactly" as contained in the manual. The manual further states that the officer should observe the suspect from three or four feet away and remain motionless during the suspect’s performance of the Walk-and-Turn test, because excessive motion will make it more difficult for the suspect to perform "even if he is sober." "People more than 60 years of age, over 50 pounds overweight, or with physical impairments should not be given this test." Further, according to the manual, "the Walk-and-Turn test requires a line that the suspect can see."

The 1984 NHTSA Manual also notes that the One-Leg-Stand test requires adequate lighting. "In total darkness, the One-Leg-Stand is difficult even for sober people." Again, the officer should be at least 3 feet away and remain relatively motionless. "Being too close – just as in the Walk-and-Turn Test – makes the test more difficult," states the manual. The officer is instructed to time the One-Leg-Stand Test and to terminate it after the end of the count by the suspect or after 30 seconds, if the person counts slowly.

Since 1984, the essential ingredients of Standardized Field Sobriety Testing has remained unchanged. That is, field sobriety tests are only valid when properly administered and properly scored in strict compliance with NHTSA standards. The reason for this is obvious - the tests measure not just balance and coordination, as noted in Bostelman, but they also measure a person’s ability to follow instructions exactly, even when his balance is unimpaired from alcohol.

Many studies have been published in scientific or medical journals which are highly critical of these Standardized Field Sobriety Tests. These studies either criticize an officer’s actual administration and scoring of the tests – i.e., "they don’t do them as trained and instructed," or they are critical of the reported accuracy of the tests in gauging impairment.

In a study written by Dr. Spurgeon Cole, the author is highly critical of the reliability of the SFSTs when used to prove impairment or alcohol levels. In "Field Sobriety Tests: Are they designed for Failure?" Perceptual and Motor Skills (1994), Dr. Cole analyzed the 1977 NHTSA report, the 1981 NHTSA report and the 1983 NHTSA Field Evaluation report, and observed the following (as reported in the Horn decision supra):

1. 47% of the subjects in the 1977 NHTSA laboratory study who would have been arrested actually had BACs below 0.10; 

2. in the 1981 NHTSA report, 32% of the subjects were incorrectly judged to have BAC’s at or above 0.10;

3. the accepted reliability coefficient for standardized clinical tests is .85 or higher, yet the reliability coefficients for the SFSTs as reported in the NHTSA studies, ranged from .61 to .72 for the individual tests and .77 for individuals that were tested on two different occasions while dosed to the exact same BAC. More alarming, inter-rater reliability rates (where different officers score each subject) ranged from .34 to .60, with an over-all rate of .57.

As further stated in Horn:

Dr. Cole’s study theorized that the SFSTs, particularly the Walk-and-Turn and One-Leg-Stand tests, required subjects to perform unfamiliar, unpracticed motions and noted that a very few miscues result in a conclusion that the subject failed and had a BAC in excess of 0.10. His hypothesis was that individuals could be classified as intoxicated/impaired as a result of unfamiliarity with the test, rather than actual BAC. He tested this hypothesis by videotaping twenty-one completely sober individuals performing either "normal-abilities tests" (such as reciting their addresses or phone numbers or walking in a normal manner) or the Walk-and-Turn and One-Leg-Stand tests. The results of Dr. Cole’s study were that 46% of the officers that viewed the videotape of the sober individuals performing the SFSTs rated the subjects as having had too much to drink, as compared to only 15% reaching this decision after seeing the videotape of the subjects performing the normal-abilities tests. Dr. Cole concluded:

"[The SFSTs] must be held to the same standards the scientific community would expect of any reliable and valid test of behavior. This study brings the validity of field sobriety tests into question. If law enforcement officials and the courts wish to continue to use field sobriety tests as evidence of driving impairment, then further study needs to be conducted addressing the direct relationship of performance on these and other tests with driving. To date, research has concentrated on the relationship between test performance and BAC and officers’ perception of impairment. This study indicates that these perceptions may be faulty."

In "End-position nystagmus as an indicator of ethanol intoxication", Science and Justice 2001, Vol 41: pp 113-116, published by the Forensic Science Society, the Horizontal Gaze Nystagmus test was studied under clinical experimentation. The authors concluded that the HGN has a high baseline error and a dose/response relationship that varies greatly depending upon whether the subjects BAC concentration was rising or falling. Further, the officers noted that videotapes recorded by cameras in police vehicles revealed that police officers rarely comply with the minimum requirements of the nystagmus examination procedures for which they were trained and certified.

The Science and Justice study further stated that fatigue testing determined that subjects had distinct nystagmus in one or both eyes after being awake for an average of 11.2 hours. Distinct nystagmus was noted in 55% of the group after being awake an average of 24.5 hours. In 52 videotapes of officers who arrested persons for Driving Under the Influence, only one officer conducted the HGN test in a manner consistent with the approved procedures. The study stated that "the HGN test has routinely been applied in situations where a high incidence of false positives is to be expected."

In a survey of police surgeons who attended a training seminar devoted to use of the Standardized Field Sobriety Tests pioneered in the United States (and are the subject of discussion herein), 44% of the police surgeons expressed reservations with the use of the SFSTs. "Drugs Driving - standardized field sobriety tests: a survey of police surgeons in Strathclyde" Journal of Clinical Forensic Medicine (2001) Vol. 8: pp 57-65.

In an article entitled "Psychology, Public Policy and the Evidence for Alcohol Intoxication" American Psychologist 1070 (Oct. 1983), a series of experiments performed at Rutgers University’s Alcohol Behavior Research Laboratory to test the ability of social drinkers, bartenders, and police officers’ to estimate the sobriety of individuals was reported. Each group was charged with reliably judging an individual’s intoxication. All three subject groups – the social drinkers, the bartenders, and the police officers – correctly judged the subjects’ level of intoxication only 25 percent of the time.

In other states, the laws regarding the admissibility of field sobriety tests (other than HGN) is largely unsettled. Hawaii, courts have held that the One-Leg Stand and Walk-and-Turn are non-scientific in nature, and, accordingly, prohibited the officer from testifying that a person "passed" or "failed" these tests without laying a proper foundation. State v. Ferrer, 23 P.3d 744 (Hawaii Ct. App. 2001).


The Bostelman decision perpetuates an urban myth that sobriety tests– any sobriety tests whether nonvalidated or improperly administered by a police officer – are reliable indicators of intoxication. This decision passes to the jury the unenviable task of weighing upon the validity and reliability of field sobriety tests in the vacuum of the jury room. Had the Bostelman court been given the information that was received into the record by the Homan court or the Horn court, perhaps his decision would have been different.

Defense counsel would be well advised to do their homework and be well prepared when defending a client charged with Driving Under the Influence when the testimony rests upon questionable field sobriety exercises or improperly administered or improperly scored Field Sobriety Tests. Further, even when performed properly, counsel should be prepared to establish that these tests are not foolproof and have been the subject of criticism in the legal, scientific, and medical communities.

Donald J. Ramsell is the founding Director of Ramsell & Armamentos, L.L.C. in Wheaton, Illinois. His firm has defended over 7,000 DUI cases since 1986. Recently, he was certified as a field Sobriety Testing Instructor using NHTSA Standards.

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