In order for law enforcement personnel to make a
DUI arrest, they must first establish what is known as “probable cause.”
Essentially this means they must reasonably suspect that you are breaking
the law by being intoxicated while driving. However, they must establish
this suspicion through legally acceptable means, and they frequently use
widely-accepted field sobriety tests to do so. Many people know of at
least one of these sobriety tests, and most people think they’re
either highly accurate or even infallible. However, those same people
are often stunned to learn the truth: field sobriety tests are notoriously
inaccurate and provide false positives leading to unlawful arrests fairly
frequently. Let’s look how some of the most common field sobriety
tests work and see how often they are inaccurate.
The Origin of Field Sobriety Tests
Back in the late 1970s, the NHTSA and the Southern California Research
Institute were tasked with determining which field sobriety tests were
the most accurate in an attempt to reduce the amount of errors and false
arrests. After extensive testing, researchers determined that the three
most accurate tests were the walk-and-turn test, the one-leg stand test,
and the horizontal gaze nystagmus test.
However, even when all three of these tests are administered together and
done properly, they were still only correct 82% of the time. That’s
nearly one in five instances being a false positive leading to an arrest!
Used individually, these tests are even more inaccurate, which could factor
heavily in your case.
Walk & Turn
The walk-and-turn test is perhaps the most well-known field sobriety tests.
This test essentially requires you to divide your focus by walking in
a straight line and turning while listening to instructions given by the
administering officer. You will be required to take nine steps in a straight
line, heel-to-toe fashion, then turn on one foot and walk the opposite
direction. This test used to be horrendously inaccurate, and even with
standardization, its accuracy rose to just 68%.
The one-leg stand is a particularly difficult task for many people to do
successfully even while completely sober. In this test, you will be required
to stand on one foot with the elevated foot about six inches off the ground
and your toes pointed forward. You will then have to count out thirty
seconds. However, many people don’t have the physical ability to
successfully complete this test—it’s not a simple task after
all, particularly for those who don’t have good balance in the first
place. Standardizing increased this test’s accuracy as well, but
only up to 65%, meaning it’s only correct a little over half of the time!
Horizontal Gaze Nystagmus
This is perhaps the most accurate test in that it doesn’t require
any difficult physical activities and is the most difficult for an intoxicated
individual to pass. This test essentially is a test for nystagmus, which
is a condition where the brain loses the ability to properly control eye
muscles when intoxicated by drugs or alcohol. Officers test this by simply
holding up a pen or their finger and then asking you to follow it with
your eyes without moving your head. If your eyes rapidly jerk back and
forth while following the target, then the officer will suspect you are
intoxicated. While this test seems almost foolproof, it’s not infallible.
Even with standardization, the accuracy only rose to 77%.
Because these tests are notoriously unreliable, your arrest may not have
been made on legal or justified grounds. For this reason, you should not
hesitate to speak with a Murfreesboro DUI lawyer who can help you fight
back against your charges. When you call Crain & Flatt Attorneys at Law you can trust that you have a skilled and experienced legal advocate taking
care of your case with your best interests at heart. Attorney Crain has
proudly obtained a 10.0 Superb rating from Avvo as well as been named
a Top 100 Trial Lawyer by The National Trial Lawyer twice thanks to his
years of dedication to his clients, exceptional legal ability, and unwavering
If you or a loved one are facing DUI charges, don’t delay! Let Crain
& Flatt Attorneys at Law review your case today!
Call our office at 888-988-5578.
All accuracy statistics courtesy of