Field Sobriety Tests

Field Sobriety Tests – 100% Voluntary

Field Sobriety Tests, or FSTs, are a central part of nearly every Ventura DUI case. They are also 100% voluntary, but the law does not require an officer to inform you of this fact. Law enforcement officers are very good at getting people to perform FSTs, due in part to the fact that most people want to be cooperative, and are nervous and scared. They are also designed to be failed, and are rarely administered correctly. Your performance on them will most definitely be used against you.

Standardized and Validated FSTs – Only 3

In the 1970's, the National Highway Traffic Safety Administration board performed a number of studies with the goal of understanding which FSTs actually indicate alcohol impairment. As a result, many of the FSTs that were previously in use have been disregarded as ineffective. Modernly, there are on 3 FSTs that have been standardized and validated for use in a DUI investigation:

  • Horizontal Gaze Nystagmus (HGN);
  • One Leg Stand;
  • Walk and Turn.

Must be Administered Correctly

A standardized test means that the officer is to administer the test in the same method every time, and also look for the same cues during your performance of the test every time. A validated test means that there is some correlation between your performance on that test and whether or not you are under the influence of alcohol. However, in order for your performance on these three FSTs to have any reliability, the officer must administer the test in the correct manner and must note the correct cues.

HGN – Horizontal Gaze Nystagmus

This is the first FST the officers in a Ventura DUI investigation usually have you perform. In the HGN Test, the officer holds a pen, finger, or flashlight about a foot from your face and moves it from side to side. What the officer is looking for is called nystagmus, which is the involuntary jerking or bouncing of the eyes as it attempts to track a horizontally moving object.

Present at Low Blood Alcohol Levels

HGN is typically present when someone has alcohol in their system. However, HGN can be present at very low alcohol levels, and can also occur naturally without alcohol being present. As a result, the fact that the officer might claim to have observed HGN does not in and of itself show that someone is under the influence of alcohol.


The HGN test is only standardized and validated if the officer is eye to eye with you, which is why the test is supposed to be performed with you standing up. The officer must tell you to keep your head still, and to track the object as it moves from side to side by moving your eyes only. The object should start in the middle, and move slowly out to about your shoulders, where the officer should hold the object still for about two to four seconds, and then the object should be moved to the other side and held still again.


As this process is repeated, the officer should be looking at your eyes for certain cues. On the HGN test, there are 3 possible cues each eye (for a total of 6), and 4 or more may indicate impairment. The cues on the HGN test are lack of smooth pursuit, onset of nystagmus prior to 45 degrees, and nystagmus at maximum deviation.

Officer Mistakes

The HGN test is not always administered correctly, and many officers note their observations on questionable cues that have not been validated.

One Leg Stand

The One Leg Stand test is usually the second FST that the officer will ask you to perform. Prior to your performing the test, the officer must explain that you are to stand with both hands at your sides, raise one foot 6-8 inches off of the ground, and count to 30 seconds. The officer also must demonstrate how the test is performed after explaining it, and ask you if you understand how to do the test. Among the cues that the officer is to look for are hopping, putting your foot down, raising your arms, and swaying, two or more of which may indicate impairment.

However, in order for your performance on the One Leg Stand test to have any significance, the officer must explain and demonstrate how to do it according to the NHTSA guidelines.

Walk and Turn – 2 Phases

The Walk and Turn test is usually the third FST that the officer will ask you to perform in a Ventura DUI investigation. There are two components to the Walk and Turn test: an instructional phase and a performance phase. Prior to asking you to perform this test, the officer must explain that you are to stand with both hands at your sides, with the heel of your right foot touching the toe of your left foot. This is called the starting position. The officer must also demonstrate how to stand in the starting position after explaining it. During this phase, the officer should note whether you can maintain your balance in the starting position.

Performance Phase

The officer must explain that you are to take nine heel-to-toe steps out along an imaginary line, keeping your hands at your sides the entire time. On the ninth step, you make what is called a pivot turn, and then take nine heel-to-toe steps back along the same imaginary line. Sometimes, depending on where you are doing the FSTs, the officer will have you follow a painted line, or even a crack in the concrete. The officer must also demonstrate how to perform the Walk and Turn test, including the turn.

Validated Cues

Among the cues that the officer is to look for are starting too soon, missing heel to toe, stepping off line, raising your arms from your sides, taking the wrong number of steps, making an improper turn, and stopping walking.  In all, there are a possible eight total cues, and two or more may indicate impairment.

Other Factors May Affect Performance

There are numerous factors that can affect your performance on the One Leg Stand and Walk and Turn tests, including injuries, balance issues, age, footwear, and the conditions the test is performed in, including the surface of the ground.

Certified by Ventura County Sheriff's Department in FSTs

Ventura County DUI attorney Jasen Nielsen is P.O.S.T. certified in Field Sobriety Tests by the Ventura County Sheriff's Department. This is the same training and certification received by law enforcement officers throughout the state. I know how the Field Sobriety Tests are to be administered, what cues the officers are looking for, the mistakes they commonly make, and how to use your FST performance to your advantage.

If you have been arrested for a DUI in Ventura County, and have questions about the administration and performance of Field Sobriety Tests in your case, please call me at (805)564-4DUI for a free consultation.

Keep Driving

After a DUI, you only have 10 days to request a hearing with the DMV. If you don't, your license will automatically be suspended, and you won't be able to drive at all for 30 days - not even to work! Give me a call today and I'll request your hearing for you so you can keep driving.

Experience Gets Results

DUI punishment is always increasing, and the penalties are always getting stiffer. Even on a first offense, jail time is a real possibility, in addition to a host of other potential consequences, including the suspension of your license, probation, fines and fees and more. I am ready today to fight your case if can be won and to help you minimize the charges and punishment if it cannot. Check out my client reviews and success stories for more.