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DUI Field Sobriety Tests (FSTs)

Once you are pulled over, the officer immediately asks if you had anything to drink. You automatically want to answer truthfully and say, “one beer”. This prompts the officer to ask you to step out of the car to perform a couple of sobriety tests just to make sure you are okay (not impaired) to drive. Should you even attempt to give your best efforts at these tests? NO!!!! You are not required to perform the FSTs even when the officer is “requesting” you to perform them. Just understand, if you refuse to perform the FSTs, the officer may arrest you on the spot. However, even if you have not had one sip of alcohol and you perform the FSTs, you are more than likely going to “show signs of impairment”. After you preform three separate tests, you are pretty sure you passed with flying colors. Reality is, guess who is going to be taken to the station to get their blood drawn because the officer observed “signs of impairment” during the FSTs? That’s right, you!

There are three “standardized” FSTs: (1) Horizontal Gaze Nystagmus (HGN), (2) Walk and Turn (WAT), and (3) One Leg Stand (OLS). These “standardized” tests are recognized by the United States National Highway Traffic Safety Administration (NHTSA). There are other non-standardized FSTs that are considered less reliable and will not be discussed here.

First, what does standardized mean? Basically, the FSTs are to be given the same way every single time. Standardized does not mean valid. These test do not even measure intoxication or blood alcohol level.

HGN Test

The HGN is the “eye” test, where the officer asks the driver to follow the object (usually pen or finger) with his/her eyes from side to side while not moving his/her head. The officer is looking for the eyes to jerk for a total of six (6) “clues” of impairment. Any jerkiness of the eyes suggests alcohol is affecting the body’s motor control. However, certain medication and sleep deprivation can too cause the eyes to jerk and/or show the same “clues” of impairment.

WAT Test

The WAT is the test in which the officer asks the driver to walk 9 heel-to-toe steps on a line in one direction and then, to turn, and walk 9 heel-to-toe steps in the opposite direction down the same line. This test is testing balance and coordination. Some of the “clues” the officer is looking for is for the driver to get out of heel-to-toe instructional stance, start the test too soon, step off the line, turn the wrong direction, etc. There are several physical conditions that may cause “clues” resulting in false positives (i.e., knee problems, ankle problems, inner ear conditions, head injury, etc.).

OLS Test

The OLS is basically a balance test. The officer will ask the driver to stand on one leg with the other leg 6 inches off the ground while counting to 30. The “clues” the officer is looking for are the inability to be able to keep foot off the ground, hopping, swaying, etc. Physical conditions and medications can also result in false positive “clues”. Let’s be honest, some people can’t walk and chew gum, let alone keep their balance on one leg!!

While you may think you passed the FSTs with flying colors, you can guarantee the officer saw a number of “clues”. The overall performance on the FSTs will help the officer in deciding whether probable cause exists to arrest you for DUI/DWI. So do yourself a favor and DO NOT perform the FSTs. Your performance will only be used against you.

If you, friend or family member have been arrested for any DUI charge contact POUNDSTONE SCOTTEN, PLLC at (480) 447-0790, right away. POUNDSTONE SCOTTEN, PLLC is here to protect your interests. Attorneys are available 24/7.


The information provided in this website is meant only as a general description of the current laws as of the date of the writing. It is not meant to be an exhaustive discussion of all the nuances of the law and is intended to be only an overview. Many issues may appear simpler than they are, and an individual should always contact an attorney to obtain a complete, accurate interpretation of the law given the individual’s particular circumstances. POUNDSTONE SCOTTEN, PLLC makes no representations as to how the law would affect a particular situation and intends only to illustrate areas of concern and give general information.

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