Field Sobriety Testing
Standardized Field Sobriety Tests
Standardized Field Sobriety Test (SFST) battery is composed of three
tests: Horizontal Gaze Nystagmus (HGN), Walk-and-Turn (WAT), and One-Leg
Stand (OLS). The tests were developed by the National Highway Traffic
Safety Administration (NHTSA) in the late 1970's. In 1981, law
enforcement officers began using NHTSA's Standardized Field Sobriety
Test (SFST) battery at roadside to help determine whether motorists who
are suspected of DWI have blood alcohol concentrations (BACs) greater
than 0.10 percent. Since 1981, however, many states including Texas have
implemented laws that define DWI at BACs below 0.10.
validity of SFST results is dependent upon officers following the
established, standardized procedures for test administration and
scoring. According to NHTSA when properly administered and scored,
under laboratory conditions, the accuracy of the SFSTs in
correctly identifying intoxicated drivers is as follows
means that even under laboratory conditions, the HGN was wrong 23% of
the time, the WAT 32% and the OLS 35% of the time. Additionally,
NHTSA's own research emphasizes that test results are valid only when
administered in strict compliance with NHTSA protocol. If anyone
of the standardized field sobriety elements is changed, the validity is
compromised. It is therefore imperative to contact a skilled Sugar
Land DWI Lawyer to review
the manner in which the SFSTs were administered. An experienced
DWI lawyer may be able
to suppress the results of an improperly administered test.
Sober People Fail Field Sobriety Tests Too
It is not uncommon for a completely sober person to
fail a field sobriety test. The tests are designed to place a
person in an unnatural and uncomfortable posture. The police do
not explain how the tests are graded nor is the subject offered an
opportunity to practice or a second chance. The NHTSA training
manual acknowledges that individuals with back, leg, knee problems and
those over the age of 65 and persons more than 50 pounds overweight are
likely to have difficulty performing the tests.
Horizontal Gaze Nystagmus (HGN)
"Nystagmus" means an involuntary jerking of the eyes. HGN refers to an
involuntary jerking occurring as the eyes gaze toward the side. In
addition to being involuntary the person experiencing the nystagmus is
unaware that the jerking is happening. The theory behind the test is
that nystagmus becomes readily noticeable when a person is impaired.
administering the test the officer has the subject follow the motion of
a stimulus with the eyes only. The stimulus may be the tip of a pen or
penlight, an eraser on a pencil or a fingertip. As the eyes move from
side to side each eye is examined for three specific clues:
Lack of Smooth Pursuit - does the eye move slowly or does
it jerk noticeably?
Distinct Nystagmus at Maximum Deviation - when the eye
moves as far to the side as possible and is kept at that
position for several seconds, does it jerk
Onset of Nystagmus Prior to 45% - as the eye moves to the
side, does it start to jerk prior to a 45% angle?
Officers frequently fail to properly administer the HGN. It is
crucially important for your attorney to review the videotape, if
available to ascertain whether the test was properly administered or
whether suppression of the results is possible.
Walk & Turn (WAT)
is a divided attention test consisting of two stages: Instruction Stage;
and Walking Stage. In the instruction stage, the subject must stand
with their feet in heel-to-toe position, keep their arms at their sides,
and listen to instructions. The subject must maintain the heel-to-toe
position and may not begin walking until all instructions are given. In
the Walking Stage the subject takes nine heel-to-toe steps, turns in a
prescribed manner, and takes nine heel-to-toe steps back, while counting
out loud and watching their feet. Officers observe the subject's
performance for eight clues:
subject who exhibits two or more clues fails the test. Scoring is
entirely subjective and within the officer's discretion.
One Leg Stand (OLS)
is also divided into two stages. In the Instruction Stage, the subject
must stand with feet together, keep arms at side and listen to
instructions. In the Balance and Counting Stage, the subject must raise
the leg of his choice approximately 6 inches off the ground, toes
pointed out, keeping legs straight. While looking at the elevated foot,
count out load in the following manner: "one thousand and one", "one
thousand and two", etc, until told to stop. The officer will instruct
the subject to stop after 30 seconds. The subject is observed for the
sways while balancing
uses arms to balance
puts foot down
A subject who exhibits
2 or more clues will fail the test.
Free Consultation - Call Now
Sugar Land DWI Lawyer Anthony R. Segura has successfully completed the
National Highway Traffic Safety Administration DWI Field Sobriety
Training Course. This is the same training that police receive.
Mr. Segura has extensive experience defending person charged with
intoxicated offenses in Sugar Land and Fort Bend County. Contact him at
281-240-DWI-1 to learn how he can help you.