Standard Field Sobriety Tests:

Posted on June 12, 2015

Mario Massillamany

Mario Massillamany

Mario Massillamany, a criminal defense attorney, has handled thousands of DUI arrests.

When someone is pulled over and the officer needs to determine whether the driver was operating a motor vehicle while intoxicated, the officer will use at least three different field tests to determine a person’s intoxication. The Standardized Field Sobriety Test (SFST) is a battery of three tests administered and evaluated in a standardized manner to obtain validated indicators of impairment and establish probable cause for arrest. They were designed pursuant to numerous federal grants and ultimately sanctioned by NHTSA (the National Highway Traffic and Safety Administration) beginning in 1984.

One important study found that officers are more likely to overestimate a suspect’s Blood Alcohol Content (BAC) if he or she submits to the field sobriety test. There have been instances reported all over the country of suspected drunk drivers who allegedly “failed” the field sobriety test, until video evidence of the testing surfaced, revealing that the suspect had actually passed. Perhaps the most shocking fact of all is that there is no conclusive evidence that a person who is sober will perform better on an FST than a person who is intoxicated. Remember these are voluntary tests unlike breathalyzers which are mandatory (refusal results in automatic one year license suspension).   

The first test is known as the One-Leg Stand Test. For this test the officer must instruct the driver to raise his/her foot six inches off the ground and count out loud until otherwise instructed. The driver must keep his hands by his sides, keep his toes pointed outward, and keep looking down. If one balances with one’s arms, stops the test, puts the foot down, or forgets to count, one must start the test again. If the driver fails the test twice, then he/she may be arrested for driving while intoxicated. This test measure the driver’s ability to focus on a number of small tasks at once and is called a divided attention test.

The second test is called the Walk and Turn Test and is also a divided attention test, testing the driver’s abilities to do multiple tasks at one time. The officer must explain the directions and must demonstrate for the driver. The driver will be instructed to walk in a line, take nine heel-to-toe steps, and count out loud, then turn around by pivoting on his front foot and walk back doing the same thing. The officer will look for imbalance, not counting, or inability to walk in a straight line. The driver must make at least two errors to be arrested for drunk driving.

The final test is the Horizontal Gaze Nystagmus Test. This test involves the driver holding his head still and following a pen or light only with his eyes that the officer is holding. The officer is looking for involuntary eye movements; this can be a sign that a driver has been drinking. This is the most accurate of the three tests with over 75% accuracy.

The driver’s performance has been highly admissible in court, however the prosecution must prove that the arresting officer has had the proper training and experience before the evidence is considered admissible. People tend to challenge the field sobriety tests because they are not very scientific, people with poor balance will likely fail the divided attention tests, and people can have a health condition that causes involuntary movement of the eyes.

Although they are widely used by police and accepted as evidence at trial, the question remains: are field sobriety tests truly an accurate barometer of a person’s level of intoxication? Many researchers say no. The most shocking fact of all is that there is no conclusive evidence that a person who is sober will perform better on an FST than a person who is intoxicated.

So with summer starting and the police on the lookout for those driving while intoxicated, drive safe and if drinking have a designated drive to avoid being arrested for driving while intoxicated. However, if you or someone you know has been subject to a Standard Field Sobriety Test, resulting in an arrest for driving while intoxicated please call DUI defense attorney Mario Massillamany at Massillamany and Jeter LLP for a free consultation to discuss your options.

Mario Massillamany is a founding partner of the law firm of Massillamany & Jeter LLP and serves as Team Leader for the firm’s Criminal Law Practice Area. For more information on this topic, please contact Mr. Massillamany at (317) 432-3443 or by e-mail at:


This article is not intended to serve as legal advice. Should you have questions about this topic, you should consult with a licensed lawyer.


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