Richard Ryczek:
Standardized Field Sobriety
Evaluation
NHTSA or the National Highway Transportation
Safety Administration developed three Standardized field
sobriety tests to help officers determine whether a DUI
suspect's blood alcohol content exceeds .08 percent. The
three Field Sobriety Tests are the Horizontal Gaze
Nystagmus, the Nine Step Walk & Turn, and the One Leg
Stand.
Horizontal Gaze Nystagmus Test (HGN)
What is the HGN and how is it performed?
Horizontal Gaze Nystagmus (more accurately lateral gaze
nystagmus) is a medical term describing the involuntary
jerking of the eyes. Officers perform this alleged
"scientific" field sobriety test on your eyes. With your
head still he instructs you to follow his pen with your
eyes as he moves his pen (he will call it a "stimulus" to
make the test sound more scientific) back-and-forth across
your field of vision. As he moves his pen from side to
side, he watches your eyes to see whether they jerk
involuntarily; he is trained that central nervous system
depressants (like alcohol or antidepressants) cause this
involuntary jerking.
He is trained to perform three different tests to detect
this involuntary jerking, and assess a "clue" for each time
he sees the jerking The first test is called Lack of Smooth
Pursuit. The officer holds the stimulus 12-14 inches from
your face and moves it from right to left. He watches to
see whether your eyes move smoothly or if they move like a
windshield wiper moving across a dry windshield. Lack of
smooth pursuit is present when the eyes move in a jagged
motion like a dry windshield wiper and the officers
assesses two clues if he sees lack of smooth pursuit in
each eye.
The second test to detect nystagmus is called Distinct
Nystagmus at Maximum Deviation. Here, the officer moves the
stimulus to the far end of your peripheral vision. Once
your eyes reach the maximum deviation, the officer holds
his pen in that position for four seconds (at least). He
looks to see whether your eyes remain still or whether they
exhibit a pronounced jerking motion. If your eyes exhibit
this pronounced jerking motion, then distinct nystagmus at
maximum deviation is present, and the officer assesses two
clues if he sees distinct nystagmus at maximum deviation in
each eye.
The third and final test the officer performs to detect
nystagmus is called Onset of Nystagmus Prior to Forty-Five
Degrees. The officer moves his pen slowly from the center
of your face to the side of your face. If your eyes begin
to jerk prior the officer reaching a forty-five degree
angle from the center, then you the officer will say you
have onset of nystagmus prior to forty-five degrees.
The HGN a progressive evaluation. In other words, as
your level of intoxication increases you begin to exhibit
lack of smooth pursuit first, then distinct nystagmus at
maximum deviation, and finally onset of nystagmus prior to
45°. Officers testify that your alcohol content exceeds
.08% when your eyes exhibit four or more clues on the HGN
evaluation. To support their position, they cite studies
conducted by NHTSA. However, the NHTSA studies are flawed, and provide no
scientific basis for this claim.
Why the HGN test is not a good test.
First the NHTSA studies concluded the HGN test is only
77% accurate; this assumes that the officers conducted the
test correctly. We all have nystagmus, however most of the
time it is not detectable by the human eye; alcohol and
drugs merely exaggerate this natural nystagmus to make it
observable. Additionally, many people have an observable
natural nystagmus. These factors contribute to false
positive results on the HGN test.
Many officers perform this test incorrectly. Since the
HGN test is considered a scientific test, the officer must
administer the test the same way that it was validated. The
National Transportation Safety Administration (NHTSA)
validated the HGN test by performing it on subjects in a
controlled environment. NHTSA mandates that the officer
must perform the test according to their strict guidelines
or the results are invalid. I have had a great deal of
success convincing judges to suppress HGN results when
officer administered the test incorrectly. This means the
jurors in your case will never know that the officer
administered the HGN test on you.
Furthermore, NHTSA's study validating the HGN test is
flawed in two ways. First, NHTSA used a flawed scientific
method in analyzing their data, and second their data are
inconsistent. The scientific method is erroneous because
they grouped four clues (lack of smooth pursuit and
distinct nystagmus at maximum deviation in both eyes)
together with six clues on the HGN (add onset prior to 45
°) in the validation study. NHTSA wanted to know how
many clues indicates a BAC exceeding .08 percent. NHTSA
should have studied DUI subjects with four HGN clues to
determine whether their BACs exceeded .08 percent, then
study DUI subjects with six HGN clues asking the same
question. Instead, NHTSA studied DUI subjects with four HGN
clues with those having six clues. Six HGN clues indicates
.08 or greater while four HGN clues does not, however
NHTSA's study did not seek to address this issue. NHTSA's
study is also flawed due to inconsistent data. Some NHTSA
studies conclude that four HGN clues indicates a BAC
exceeding .08 percent while NHTSA trains officers in more
advanced DUI courses that four HGN clues means that the DUI
subject's BAC is lower than .05%; under Georgia law the DUI
suspect is presumed not to be impaired.
Your lawyer must be well versed in the NHTSA studies
allegedly "validating" this HGN test in order to either
exclude the test from your trial, or show the jurors that
the HGN test is meaningless through cross-examination.
PHYSICAL AND DIVIDED ATTENTION TESTS
There are two additional field sobriety tests
recommended by NHTSA. These are the 9-Step Walk and Turn
and the One Leg Stand. These considered divided attention
tests because they test your coordination while they test
your ability to process and remember information.
9-Step Walk and Turn
The walk and turn test tests your coordination in
addition to your ability to recall and process information.
There are two phases to this test. The first phase is the
instructional phase, and the second phase is the
performance phase.
During the instructional phase, the officer tells you to
place your right foot in front of your left foot, touching
heel to toe. He should tell you to remain in that position
until he tells you to begin. The officer will tell you how
perform the test during the instructional phase, and he
will watch to see if you are able to keep your balance
while he gives these instructions. She will count off if
you:
- Begin the test too soon (before she tells you to
begin).
- Break the heel to toe stance while she instructs
you.
During the performance phase she will watch to see
whether you followed instructions and whether you were able
to keep your balance while walking the straight line. She
will count off during the performance phase if you:
- Miss heel toe while walking a straight line.
- Step off the imaginary straight line.
- Use your arms for balance.
- Stop while walking.
- Take the incorrect number of steps.
- Turn in a way that is different than the officer
instructed.
One Leg Stand
The one leg stand also tests your coordination and your
ability to comprehend instructions. During this test the
officer tells you to raise the leg of your choice
approximately six inches off the ground with your toe
pointed straight. She then tells you to remain balancing in
that position with your arms down by your sides, looking at
your foot, and count by one thousands until she tells you
to stop. Once you begin the test, she will look at her
watch and stop the test once thirty actual seconds have
elapsed. She will count off if you:
- Hop
- Sway
- Use your arms for balance
- Put your foot down
Field Sobriety Tests Do Not Accurately Determine Whether
Driving Ability is Impaired.
Everybody is different. NHTSA developed these tests in a
controlled environment. Their "test subjects" were dosed
with alcohol and NHTSA studied the test subjects' ability
to perform these tasks at various blood alcohol levels. The
conditions to which NHTSA's test subjects were subjected
are far different from the testing conditions to which a
DUI suspect is subjected.
First, NHTSA's initial test subjects were not under
investigation for DUI. They were volunteers who agreed to
drink alcohol and perform various tasks in a gymnasium. A
typical DUI suspect has been pulled over by the police. He
begins his experience with a sinking feeling as he sees the
flashing blue lights behind him. He pulls his car to the
side of the road and the officer tells him to step out of
his car to perform field sobriety tests. NHTSA's test
subjects did not experience a DUI suspect's level of
anxiety. NHTSA's volunteers did not begin their experience
in the comfort of their own car. Their heart did not
quicken as they saw the blue lights behind them. Their
hands did not begin to shake as the officer told them to
get out of the car. They did not have an officer with a gun
and a nightstick ready to take them to jail for failing to
satisfactorily perform the tests. Most jurors understand
that Field Sobriety tests are difficult under the best of
circumstances. Jurors also understand that your performance
on field sobriety may be the result of nervousness rather
than alcohol impairment.
Second, FST's do not test your driving ability. You are
not guilty of DUI unless the State can prove that you were
incapable of driving safely (or you were above the legal
limit). Officers say that poor performance on FST's is an
indicator of impaired driving ability. This is simply not
true. People practice driving everyday. DUI suspects only
get one chance to perform FST's. Officers do not let DUI
subjects practice these tests. Even worse, the officers
never tell the suspect what is required to pass the test so
the suspect never knows what is expected of him. Again,
everybody is different. Most people perform less well on
FST's under such stressful conditions. Therefore, there is
no direct correlation between driving ability and
performance on FST's. One does not stand on one leg for
thirty seconds while they drive a car. These are two
completely unrelated skills.
NHTSA claims to have conducted "field" validation
studies under arrest conditions; however their findings are
unscientific as shown by their own data. Police officers
often claim FST's are 91-94% accurate in making the arrest
decision at a .08 level. To support this claim, they cite
the "California Study". However, researchers used faulty
science to "validate" FST's. Most importantly they
validated FST's at a .08 level by using group of subjects
with a sample mean (average) of .150 grams of alcohol. (see
NHTSA's table below). To validate FST's at the .08 level,
the researchers should have studied subjects closer to .08.
Instead the researchers studied subjects who were obviously
impaired.
To provide a real-world example of NHTSA's flawed
method, suppose that you want to know whether NASCAR fans
can accurately predict whether cars exceed a 65-mile per
hour limit. To scientifically answer that question, your
NASCAR fans must see cars traveling near 65 miles per hour.
The average speed of the cars tested should be close to 65
mph, the desired discrimination point, and the fans must
guess whether each car exceeded 65 mph. A validation study
is meaningless if the NASCAR fans watch cars traveling at
135 mph. 100% of the NASCAR fans will accurately predict
the cars exceed 65 mph. The same is true when the slower
cars travel at 20 mph. The fans will correctly predict
those cars are slower than 65. Although the fans would
accurately predict speed over and under 65 mph under those
circumstances, the study does nothing to truly validate
predictions at 65 mph.
Similarly, NHTSA studied DUI arrestees with mean BAC's
of .150 and non-arrest subjects with a mean BAC of .045 in
the California study. In other words, those who were
arrested, were obviously over a .08 since the average
arrestee was .150 while the average non-arrestee was
.045.