Ten Things Most Lawyers Don't Know About Horizontal Gaze Nystagmus Field Sobriety Tests

The National Highway Transportation and Safety Administration (NHTSA) recommends a speed breakdown when checking smooth pursuit. Failure to follow that speed can cause many people, even those that are totally alcohol free, appear to have nystagmus. NHTSA recommends a speed of two seconds from midline to the far gaze.

According to the largest study conducted to-date, ten percent of the population have an onset of nystagmus before 45° with a zero percent BAC. And, another ten percent have an onset of nystagmus at 45° that are totally alcohol free.

Age has a direct affect on HGN when looking for smooth pursuit. The rate of smooth pursuit falls beginning in the early 30's.

HGN is a divided attention test. It is not a simple test as first thought. Studies have shown that the presence of smooth pursuit is heavily influenced by the presence of any undetected peripheral activity, i.e., cars going by, people moving around, etc. The test needs to be done in almost complete blackout conditions.

Background activity can affect smooth pursuit and result in nystagmus, i.e., the officer’s trying to perform the nystagmus test and in your periphery you can see your vehicle being towed away.

The list of causes of nystagmus other than alcohol is well known. Possible sources of nystagmus include Parkinson’s Disease, Progressive Supra Nuclear Palsy, Cerebral Disorders, Encephalopathy, Alzheimer’s Disease, Large Cerebral Lesions, i.e., someone suffering from Epileptic Seizures or any form of degenerative disorder.

A number of psychiatric conditions can affect smooth pursuit including Schizophrenia, and Psychosis. 

Nicotine affects smooth pursuit.

Nystagmus does not significantly affect vision acuity. Most people will move their head when looking at a target of more than 15° off center line. So trying to determine nystagmus onset or at max deviation at or around 45° is of little relevance.

The reliability of HGN and it’s component parts, i.e., lack of smooth pursuit. Nystagmus at max deviation and an onset prior to 45° is problematic.

ATTACKING FIELD SOBRIETY TESTS

When a driver is stopped by a police officer, especially at night, the officer will observe the driver for the signs of alcohol consumption and impairment. The Nation Highway Transportation and Safety Administration (NHTSA) listed a number of potential clues for the officer to look for, including rumpled clothing, an odor of alcohol, red eyes, glassy eyes, poor coordination, and loud or slurred speech.

Researchers have also examined indications of intoxication in an attempt to make more accurate judgments. Several general conclusions can be drawn:

While individual clues (e.g., red eyes, slurred speech) occur at different BAC levels on the average, there is a wide variation, and

Some people (probably chronic alcoholics) do not show any expected clues.

The difficulty in judging intoxication, combined with the high number of alcohol related traffic incidents, led NHTSA to develop a set of standardized sobriety tests. These were introduced in the mid-1980's and consisted of three tests: (1) Horizontal Gaze Nystagmus (HGN), (2) Walk and turn, and (3) One leg stand. HGN involves assessing the driver’s eyes for jerkiness (Nystagmus) when following a moving object or when held to the side. All three tests are standardized and should be administered, scored, and interpreted the same way each time. Often in cross-examination, a DUI defense expert will show that the police officer is not adequately trained to administer these tests, and the jury in many cases will disregard a significant portion of the driver’s performance of these tests based on that cross-examination. This is a major area of DUI defense.

However, even if they are conducted correctly, there are many limitations to the tests in determining of someone is intoxicated. A partial list includes:

Lack of norms for how sober people of different ages perform (there is no testing to show the variance based upon age, weight, etc., whether male or female)

Use of blood or breath alcohol concentration, rather than some index of impairment as a criteria of whether or not to arrest someone.

Limited investigation of the effects of fatigue, anxiety or fear on performance. No research has been done on how performance on the tests relates to driving impairment.

Considerable variability between the different officers in how they administer and score the tests, even when the tests are improperly administered is not recognized.

Failure to report data back to NHTSA, including false positive arrests-the officer finds someone fails the SFST’s, he or she is taken to the station, and blows into a breath device well below a .08% BAC. This is often referred to as a false positive. None of these are reported back to NHTSA to be incorporated into the studies to show how the officers in the field actually perform, and how the arrests actually correlate to a positive showing on the SFST’s. A good DUI expert will cross-examine the police officer regarding field sobriety testing from a scientific perspective and show the shortcomings of these tests, and while these tests in many instances are completely meaningless.

Administrative Per Se (APS) Zero Tolerance Law

Effective January 1, 2009

It is unlawful for a person who is on probation for a DUI offense to operate a motor vehicle at any time with a BAC of 0.01% or greater. Violation(s) of the law will result in a 1-year suspension of your driving privilege. Refusal or failure to complete a preliminary alcohol screening (PAS) or chemical test while on probation will result in a 2-year revocation of your driving privilege. Two or more prior DUI convictions within ten years will result in a 3-year revocation of your driving privilege. You will not get a restricted license for any of the above violations.

Effective July 1, 2009

If you have a prior DUI conviction(s) and are convicted of driving with a suspended driver license, you will be required to install an Ignition Interlock Device (IID) for up to three years depending on your driving record.

Critical Examination of the "Margin of Error" and "Uncertainty" in Breath Alcohol Testing

In every breath alcohol concentration (BAC) test, there is a great “margin of error” or “uncertainty”. This margin of error, or uncertainty, is a documented scientific fact.

Every client I have represented who had a breath test, has had a margin of error in that breath testing that potentially worked in his/her favor.

In every DUI trial, there arises that point when the prosecution’s expert tries to relate the breath alcohol concentration (BAC) test result to the time of driving. It is key to the prosecution in any DUI case, to establish  what the individual’s BAC was at the time of driving. It is essential to establish this in order to establish the crime. The BAC test is taken anywhere from 30 minutes to several hours after the time of driving. Therefore, to determine what the BAC was at the time of driving, the prosecution’s expert must engage in a process known as Retrograde Extrapolation, or as I like to refer to it, “voodoo science”.

It is imperative to the prosecution’s case that the prosecution’s expert establish what the BAC was at the time of driving. The prosecution’s expert will attempt to do this through testimony by estimating the number of drinks consumed by the defendant and testifying as to the BAC of the defendant at the time of driving.

It has long been known since the early 1930's, when Mr. Eric M. P. Widmark developed the first equations to calculate a blood alcohol concentration. Mr. Widmark determined that a degree of “uncertainty” exists in the establishing of a breath alcohol concentration. Mr. Widmark found two areas of “uncertainty”. He referred to one as the “rho factor” (food content in the stomach), and the other as the “B slope” (the burnoff or alcohol elimination rate).

Just recently, a new peer reviewed article has appeared expanding the number of areas of “uncertainty”. In his latest, and what I believe to be his seminal work, Rod G. Gullberg has raised the uncertainty issue to new level.

There are really eight factors of uncertainty. They are:

• Gender (male or female)
  
• Weight
  
• Rho factor
  
• BAC at time of test
  
• B slope
  
• Time
  
• Amount of alcohol in each drink
  
• Amount of drinks consumed

Under the latest peer review article by Rod G. Gullberg, it has been determined that the estimation of the number of drinks, could be off as much as ± 25%. The estimation of the BAC at the time of driving could be off ± 42%.

These numbers show that breath alcohol concentration testing is at best a guess and at it’s very worst, voodoo science.

In his article, Mr. Gullberg points out that juries are often asked to consider and weigh a blood alcohol concentration. However, they are lacking appreciation of the uncertainty of these estimates. Juries tend to assign an unmerited amount of weight to the prosecution’s expert. In his conclusion, Mr. Gullberg stated that all forensic scientists should present when testifying, a reliable estimate of uncertainty along with their opinions as to any estimates of a BAC or an estimate of the number of drinks. For example, when a state expert renders an opinion that a person had five to six drinks, he should also admit to the jury that he could be off as much as 25%, which would mean the person had as little as three drinks or possibly as many as eight drinks. THIS IS JUST A GUESS.

When a state forensic expert is testifying as to the BAC at the time of driving, and assuming he renders an opinion that the individual had a .11 BAC at the time of driving, he should also admit to the jury that taking in the uncertainty into consideration, using an error factor of .42%, that would mean that the individual had as low a BAC as a .06 at the time of driving or a BAC as high as a .16 at the time of driving.

To put the significance of this uncertainty factor into laymen’s terms, imagine you are flying an airplane from Los Angeles to New York City. Assume at the half way point in your trip, the pilot comes on the speaker and says, “We’ll be on time to land today, but we might miss New York City by a few thousand miles ending up in possibly Maine or Virginia.” Would you want to fly on that plane or on that airline ever again? The answer is no. Then why should a jury believe a breath alcohol concentration test result that can be off by ±42%?

If the state expert does not in his direct testimony, give this uncertainty, then it certainly incumbent on defense counsel to draw these numbers out of him and at the conclusion of the case, I’m sure that the defense counsel would say to the jury as I would say, “Ladies and gentle men, you’re not dealing with true science as being presented here today, you’re dealing with voodoo. When you have a scientific estimate, it’s expected to be scientific--