When a police officer pulls someone over under the suspicion of
DWI, they may ask the driver to step out of the car and perform several tasks—known
as field sobriety tests (FSTs)—to determine their level of intoxication.
The three most common field sobriety tests drivers are asked to perform
are the one-leg stand, the walk-and-turn, and the horizontal gaze test.
Since law enforcement agencies use FSTs to establish probable cause in
drunk-driving arrests, many people assume that these tests are accurate.
However, there are some studies that show how inaccurate and ineffective
these tests can be.
The History & Accuracy of Field Sobriety Tests
During the late 1970s, the National Highway Traffic Safety Administration
(NHTSA) assigned the Southern California Research Institute (SCRI) with
the task of assessing several field sobriety tests that were in use to
determine which were the most accurate. The SCRI brought in ten officers,
who watched subjects perform various tests and asked them to figure out
which test participants had a BAC level of .10% or higher.
Once the subjects have been assessed, the institute recommended that the
walk-and-turn, the one-leg stand, and the horizontal gaze nystagmus be
used to test for impairment. However, there was a 47 percent error rate
by the officers.
The NHTSA decided that the institute conduct these tests again in 1981
in an effort to reduce the error rate. Again, the results were not great.
The horizontal gaze these could correctly identify someone with a BAC
over .10 only 77 percent of the time. The one-leg stand test was correct
65 percent of the time. The walk-and-turn test was accurate 68 percent
of the time. When all three were used together, they were correct 82 percent
of the time.
Scientists will contend that these accuracy rates do not support the reliability
of standardized FSTs. In fact, when these tests are correct, they are
only indicative of BAC level, and not one’s ability to operate a
vehicle. In conclusion, these tests are not scientifically proven to determine
the proper results for a DWI arrest.
Should You Take a Field Sobriety Test?
The short answer is no. Field sobriety tests are not a requirement in Texas.
You can politely decline to take an FST. Remember, taking the tests can
only give an officer more probable cause to arrest you.
If you have been arrested for a DWI in Texas,
schedule a free consultation with our College Station criminal defense attorney at
The Law Office of Shane Phelps, P.C. today.