Field Sobriety Tests

Cases involving an arrest or charge of driving under the influence (DUI) often vary in terms of the facts involved. However, one commonality among the vast majority of cases is that drivers stopped for DUI are often asked to voluntarily submit to the Standardized Field Sobriety Test (SFST). Law enforcement personnel use the SFST to help determine whether a driver is actually under the influence of alcohol.

The results of the SFST are often the major determining factor used in making DUI arrests. This essentially means that the SFST, and the results, are pretty important if you are facing a DUI charge. If you have been arrested or charged with a DUI, it is crucial that you know the details of the SFST and how the results may impact your case.

What is the SFST?

The SFST consists of three tests that law enforcement personnel use to gather indicators of impairment and establish probable cause for a DUI arrest. The three tests of the SFST include: the Horizontal Gaze Test, the Walk and Turn Test, and the One-Leg Stand Test. All three tests are designed to elicit and measure certain responses from a possibly impaired driver.

In the Horizontal Gaze Test, law enforcement personnel essentially observe a driver’s eyes. Authorities observe the driver’s eyes as they follow a slowly moving object such as a pen or small flashlight. Law enforcement personnel are trained to look for certain indicators of impairment in each eye. These include the eye’s ability to smoothly follow a moving object and the angle and degree of any involuntary jerking in an eye. If a driver cannot smoothly follow a moving object, or there is a requisite level of jerking in his eyes, then the driver is suspected to have a BAC of .10 or greater.

In the Walk and Turn Test, a driver is instructed to take nine steps along a straight line. These steps must be heel-to-toe. After taking the nine steps, the driver is instructed to turn on one foot and return walking to his initial starting point in the same heel-to-toe manner. Law enforcement personnel are trained to look for seven occurrences that may suggest impairment. These include if a driver: cannot maintain balance while listening to an officer’s instructions, starts the test before the instructions are completed, involuntary stops the test due to imbalance, fails to walk heel-to-toe, uses his arms to balance, loses balance while turning on one foot, or takes an incorrect number of steps. If a driver shows two or more of these occurrences, then the driver is suspected to have a BAC of .10 or greater.

The One-Leg Stand Test is performed much in the way as the test name implies. A driver is instructed to stand on one leg and raise a foot approximately six inches off the ground. While standing, the driver must count out loud until told to put his foot down. Authorities time the driver for 30 seconds. Law enforcement personnel are trained to look for four occurrences that may suggest impairment. These include: a driver swaying while balancing, a driver using his arms to help balance, a driver hopping to maintain balance, and a driver putting his foot down. If a driver shows two or more of these occurrences, then the driver is suspected to have a BAC of .10 or greater.

SFST Results and Their Impact On A DUI Case

As stated above, the results of the SFST are often the major determining factor used in making DUI arrests. But how do these results impact a DUI case post-arrest? The answer varies.

Results of the SFST are considered as evidence in DUI cases. The overall strength of this evidence, however, largely depends on the cumulative total of impairment indicators/occurrences that took place among the three tests. The greater the number of indicators, then the stronger the evidence becomes.

For example, consider two different drivers. The first driver performs all three tests of the SFST. However, he only has difficulty with the Walk and Turn Test. In fact, his only difficulty with this test was that he slightly lost his balance when turning on one foot.

Now consider a second driver. This driver performed all three tests of the SFST and had difficulties with every single test. He couldn’t follow a moving object, fell over when trying to turn on one foot during the Walk and Turn Test, and failed to have the ability to raise his foot during the One-Leg Stand Test.

Given the two drivers described, it is apparent that the second driver demonstrated a higher number of impairment indicators than the first driver. SFST results will be used as evidence in both of the drivers’ cases. However, this evidence will have more strength in the case of the second driver.