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One-Leg Stand Test, A Standardized Field Sobriety Test (FST)

The National Highway Transportation Safety Administration, (NHTSA), has come up with three standardized tests that law enforcement uses in their drunk driving investigations to help determine if a suspect is under the influence. The three field sobriety tests, (FST’s), are the horizontal gaze nystagmus, (HGN), the walk-and-turn, and the one-leg stand. These together are called the FST battery. Officers use these and other non-standardized tests when conducting DUI investigations.

The one-leg stand test is considered a divided attention test because the subject has to focus on mental and physical tasks at the same time. It should be done on a hard, dry, non-slippery surface that is level. In addition, there should be adequate lighting.

At first the officer is supposed to give the subject instructions and demonstrate how to do the test. Then they ask the person if they understood the instructions and the subject performs the test. The subject is to stand with their heals together with their arms down by their side. Then the officer instructs the person to raise their leg six inches from the ground and while watching their raised foot, they are to count from 1001 to 1030. (See video demonstration.)

The test is performed while the officer looks for four clues. The clues are: 1.) The subject sways while balancing; 2.) Uses their arms for balance; 3.) They hop; and, 4.) They put their foot down. The officer gives one point for each clue seen during the test. Two or more points indicate the subject has a blood-alcohol level above .08. If the person puts their foot down three or more times within the 30-second test, it is considered a failure of this FST.

This test, when conducted using the NHTSA’s guidelines, has been determined in a 1981 study to be only 65% accurate in determining if a person’s BAC is above .10%. The studies were done again in 1998, using the .08 standard, and NHTSA claimed that the test is now 83% accurate in determining if a person’s BAC is at or above .08%. Still, this means about 2 out of every 10 people who were determined to have two or more clues were actually under the .08% standard.

A skilled San Diego drunk driving attorney can pick apart how the officer conducted the one-leg stand test, exposing flaws in the instructions, the demonstration, and how it was graded. If you have been arrested for DUI, do not just plead guilty! There may be defenses in your case that lead to reduced charges or even a dismissal!

The above blog article is by no means all-inclusive and is not legal advice. Laws may change and may not apply to your case. For the latest information or to get legal advice, speak to a DUI attorney in your area.


Contact the Law Offices of Susan L. Hartman today for your FREE telephone consult. Call 619-260-1122 or use the “Contact Us” form on this page. We welcome your call 24/7!