FST Results Questionable

Field Sobriety Tests Produce Questionable Results

Police officers in Florida commonly ask drunk driving suspects to perform standard field sobriety tests during the course of a DUI traffic stop. If the officer believes that the DUI suspect “fails” these tests – also referred to as field exercises – the officer may use this as cause to arrest the person for DUI.

Though standard field sobriety tests are a popular method used by police, there is evidence that the field exercises can be flawed. Both sober and intoxicated individuals have been shown to fail these tests. This is particularly true in the high-pressure situation of a roadside traffic stop.

A DUI defense often will closely examine the circumstances in which field sobriety tests were conducted. By proving a flaw in the field sobriety test itself, the defense may be able to demonstrate reasonable doubt on the charges of DUI.

How and Why Field Sobriety Tests Fail to Give Accurate Results

While field sobriety tests can sometimes indicate a person’s sobriety or intoxication, they cannot do so with 100 percent accuracy. This is, in part, because they do not use any quantitative or measurable data. They are based entirely on a police officer’s personal observations. Preconceptions or prejudice can influence an officer’s assessment of a suspect’s performance.

Standard field sobriety tests were initially created and vetted in a laboratory setting. These standardized settings do not account for conditions that may exist in the field, such as uneven ground, flashing lights, traffic, and other distractions.

In addition, a person’s health or physical condition can impact the accuracy of a field sobriety test. For instance, a sober driver with chronic knee pain may fail a test despite being in safe condition to drive.  

The Most Common Types of Field Sobriety Tests Used in Florida

Police officers are typically trained in a standard set of field sobriety tests. These physical tests are used to determine a person’s mental or physical impairment and ability to safely operate a vehicle.

The most common field sobriety tests used in Florida are: 

  • horizontal gaze nystagmus procedures;
  • walk and turn; and
  • one-leg stand.

Other tests include asking a suspect to count backward, recite a portion of the alphabet (for example, starting with the letter “J” and ending with the letter “Q”), stationary balance tests, and/or the finger count. These tests are not validated and are not considered to be standard field sobriety tests.

What is the horizontal gaze nystagmus procedure?

During a horizontal gaze nystagmus procedure, a police officer watches a DUI suspect’s eyes to gauge whether there are involuntary “jerking” movements. These occur as the eyes’ gaze shift from left to right. These movements can be caused by alcohol or drug consumption, or as the result of natural factors and certain health conditions.

Considerations of the Walk and Turn and One-Leg Stand 

As with the horizontal gaze nystagmus test, a person’s physical characteristics or medical conditions can impact performance on the walk and turn or one-leg stand. If a suspect has balance or coordination issues, it is far more likely that he or she will “fail” in the eyes of the officer.

For these reasons, DUI defense attorneys can address inherent and potential flaws with these tests. If you’ve been arrested for DUI and believe inaccurate field sobriety tests played a role, contact a defense attorney. Call 877-663-5110.