DUI Field Sobriety Tests

Updated on April 16th, 2024 at 08:58 pm

When a police officer pulls you over for a suspected DUI, you might wonder what rights you have during the stop and what tests they can ask you to participate in. More specifically, how different are standardized and non-standardized field sobriety tests?

Standardized field sobriety tests help law enforcement establish probable cause for a DUI arrest. Non-standardized field sobriety tests aren’t scientifically correct nor recognized by the NHTSA. They include the Finger-to-Nose touch test, the Rhomberg balance test, counting numbers backward, the ABCs, coin tricks, and the Hand Pat Test.

Usually, non-standardized tests are so complicated that sober people have difficulty passing them. If you were given a non-standard FST, the prosecutor’s case against you isn’t strong, and they might try to talk you into accepting a plea agreement to avoid the scrutiny of the trial.

Here’s more information on standard field sobriety tests to help you know what to expect.

What Are the Common Field Sobriety Tests?

The police conduct three field sobriety tests recognized by the National Highway Transportation Safety Administration (NHTSA): the Walk-and-turn test, the one-leg-stand test, and the HGN (horizontal-gaze-nystagmus) test.

The HGN Test

During this test, the driver is told to follow a stimulus (usually a pen, penlight, or an eraser on a pencil) with his eyes from side to side.

This standard field sobriety test is designed to look for nystagmus or involuntary eye jerking. While every person’s eyes involuntarily jerk to a certain degree, they begin to jerk to an earlier degree as a person’s blood alcohol concentration increases.

As the driver’s eyes follow the officer’s stimulus, the officer looks for three clues:

  • Whether the eyes move side to side smoothly or whether the eyes jerk noticeably
  • If the eyes jerk distinctly when the driver’s eyes move to the extreme and are kept in that position for four seconds.
  • If there’s jerky eye movement before a forty-five (45) degree angle as the eyes move to the side.

Both eyes are checked, beginning with the left eye. The officer moves the stimulus side-to-side twice before each eye to look for clues of nystagmus. Each “clue” in each eye is one of six points.

Walk and Turn Test (WAT)

This test examines whether the driver can concentrate on more than one thing at a time. Drivers must be able to drive and react to outside stimuli to operate a vehicle safely. Unfortunately, alcohol reduces a person’s ability to divide attention.

The WAT is separated into two phases:

  • Instruction phase
  • Walking stage

During the instruction phase, the driver must stand with their feet in a heel-to-toe position and their hands at their side while the officer explains the test instructions.

Once the officer has given proper instructions, the walking stage begins. The driver must take nine heel-to-toe steps, turn in a very specific (and unnatural) manner, and return heel-to-toe nine steps while counting the steps out loud.

During this WAT field sobriety test, the driver’s attention is divided between balancing tasks (heel-to-toe), attention tasks (counting aloud), and short-term memory tasks (recalling the instructions).

The officer is looking for eight possible signs of intoxication during the WAT test:

  • Balance during the instruction phase
  • Starts before instructed
  • Stops while walking
  • Steps off the line
  • Uses arms to balance
  • Does not touch heel-to-toe
  • Improper turn
  • Incorrect number of steps

One Leg Stand Test

The One Leg Stand (OLS) test requires the driver to stand on one leg. Specifically, the driver must raise one foot six inches off the ground, look at the raised foot, and slowly count to thirty aloud in the odd format of “one thousand one, one thousand two,” and so on.

The test is supposed to examine balance and attention. The indicators of impairment that the officer looks for during the roadside test are:

  • swaying when trying to balance
  • uses arms to balance
  • hopping
  • putting foot down

Can You Fail a Field Sobriety Test While Sober?

Although uncommon, it’s possible to be sober and still fail field sobriety tests. Police officers don’t mention that sobriety tests are insufficient and unreliable gauges of one’s sobriety.

Some reasons why the standardized field sobriety tests fail on sober drivers include the following:

  • They are subjective – They don’t have scientific backing. Instead, they depend on the police officer’s judgment which can be biased if their goal is to gather evidence to prove drunk driving. So, you may pass with one police officer and fail with the officer.
  • Pre-existing medical conditions – Physical conditions that affect a person’s balance, coordination, or mobility can impair their performance on these tests, even when they’re entirely sober. Conditions such as natural poor balance and inner ear disorders, which can affect balance, or neurological conditions, such as Parkinson’s, which can cause tremors or rigidity, may result in a false positive.
  • Anxiety – A DUI stop is an inherently high-stress situation, and it’s common for drivers to experience anxiety, fear, and nervousness. These emotional responses can lead to physical symptoms such as trembling, lack of focus, stuttering, or rapid breathing. Law enforcement officers may misinterpret these signs as indications of impairment.
  • Fatigue – Sleep deprivation or exhaustion can negatively affect a person’s cognitive and physical performance. In a tired state, drivers might exhibit poor coordination, slower reaction times, and decreased attention – all of which are also symptoms of alcohol or drug impairment.

How Do Field Sobriety Tests Affect Your DC DUI Case?

When a law enforcement officer administers a field sobriety test and determines that you’ve failed it, this assessment provides the officer with probable cause to make an arrest and charge you with driving under the influence of alcohol

However, it’s vital to understand that a failed field sobriety test alone does not constitute a conviction for a DC DUI charge. The court evaluates the totality of the evidence, and the result of a field sobriety test is just one piece of that puzzle. Other evidence may include breathalyzer or blood test results, officer testimony about your behavior, or video footage from a police dashboard or body camera.

The reliability of field sobriety tests to determine the level of intoxication is often open to scrutiny. These tests can produce false positives in different circumstances, including varied weather conditions. An experienced attorney can challenge the validity of the test results, introducing reasonable doubt into the prosecutor’s case.

A failed sobriety test can give the state prosecutor a starting point; building a successful prosecution solely on this basis can be challenging. A failed test does not incontrovertibly prove impairment or establish guilt beyond a reasonable doubt – the standard required for a criminal conviction.

Contact Experienced DUI Attorneys at Bruckheim & Patel

All DUI cases are different, and many factors can change the primary defense strategy. If you were pulled over under the suspicion of alcohol intoxication and refused to submit to field sobriety testing, call the experienced criminal defense attorneys at Bruckheim & Patel.

We can help you build a solid case to defend against the accuracy of field sobriety testing and the indicators of impairment used by law enforcement agencies. Contact us today for a quick consultation on the best approach to your case.


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