The National Highway Traffic Safety Administration has developed standardized
field sobriety tests to be used by law enforcement when determining driver
impairment. These tests were developed, studied, and seen as the most
reliable out of all field sobriety tests. However, that does not mean
they are foolproof.
Many experts have proven these tests to be designed to make individuals
fail, rather than provide accurate insight on their impairment. For example,
a completely sober individual may fail a test due to physical disabilities
or the complex and unique nature of the tasks involved. How many people
normally practice walking heel to toe or balancing on one leg for extended
periods of time?
Regardless, the more you understand about these tests, the better informed
you will be when facing them in a serious situation. Remember, field sobriety
tests are also not mandatory; but a chemical test is if you want to avoid
an automatic driver's license suspension.
What are the standardized field sobriety tests?
The three tests are systematically administered. Depending on the responses
of the person being tested, the officer may use this evidence to place
the driver under arrest. It is suggested that the three tests, used in
combination with one another, have a 91% accuracy of determining driver
The three tests are:
Horizontal Gaze Nystagmus test: This is an involuntary jerking of the eye that occurs when the eye looks
to the side. When someone has consumed alcohol, the jerking is more aggressive
and starts earlier than someone that is sober. An officer will ask a driver
to follow a pen or a flashlight with their eyes, looking for the inability
of the eye to smoothly follow the object and the distinct jerking of the eye.
Walk and Turn: This test requires that a suspect listen to and follow instructions while
performing physical movements. The officer will ask the driver to take
nine steps along a straight line, walking heel to toe. The suspect must
turn on one foot and return in the same manner. Officers look for the
inability to balance, not walking heel to toe, stepping off the line,
using arms, improper turning, or failing to take the right amount of steps.
One Leg Stand: The officer will ask the driver to stand with one foot off the ground and
count out loud by the thousands. This will show if the suspect can balance
without swaying, using their arms, hopping, or placing their foot down.
While these factors can indicate a level of impairment, the validity of
the field sobriety test can be called into question. For example, Horizontal
Gaze Nystagmus can be affected by the consumption of certain medications
and physical impairments or geographical elements may limit how long a
person can stand on one leg. Working with a DUI lawyer can help determine
the best defenses to these tests.