If you are pulled over on reasonable suspicion of DUI, the officer will likely request that you step out of the vehicle to perform a series of exercises called Field Sobriety Tests (FSTs), also known as Field Sobriety Exercises (FSEs). The purpose of FSTs is for the officer to determine if there is probable cause to make an arrest. The National Highway Traffic Safety Administration (NHTSA) has established a set of three exercises to test mental and physical performance:
The Three Standardized Field Sobriety Tests
Horizontal Gaze Nystagmus Test
If you decided to accept the request of a Field Sobriety Test, the officer will commonly begin by administering the Horizontal Gaze Nystagmus Test (HGN). The officer will pull out a penlight and ask you to look at the light without moving your head. The officer will move the light about one foot away from your face. The idea is that your eyes are supposed to jerk as they move (known as “nystagmus”) if you have been drinking, instead of following the light smoothly.
NOTE: Even though the HGN is almost always given (and administered first), it has come under criticism for being an inaccurate indicator of impairment. A significant portion of the population naturally exhibits nystagmus when sober, and the test has been shown to be unreliable when it is not administered by a qualified individual. As such, there are only a handful of qualified police officers (known as Drug Recognition Experts) who can testify at trial about a defendant’s performance on the test. In fact, some courts in Florida won’t even allow the HGN as evidence.
Walk and Turn
The next test an officer routinely gives is the “Walk and Turn.” The officer will ask you to walk in a straight line heel-to-toe for nine steps. After, the officer will ask you to make a tight turn (often in an unusual manner) and then walk back nine steps.
NOTE: Officers are recording every error you make such as using your hands for balance, incorrect turning, taking an incorrect number of steps, and even starting before you are supposed to.
One Leg Stand
If the officer administers the One Leg Stand test, you will be asked to balance on one leg and count to 30 seconds.
NOTE: Officers are observing every error you make, including poor balance and counting too fast or too slow.
Should I take a Field Sobriety Test?
If an officer asks you to perform the Field Sobriety Test, you have the right to say no. If you refuse to take an FST, then the officer can still take your refusal and his other observations as evidence against you and conduct an arrest. However, without evidence of your performance on the FSTs, it becomes more difficult to prosecute your case. Please note that your refusal may be admitted into court as evidence against you.