Field Sobriety Test

What Field Sobriety Tests Are Valid?

When the flashing lights of a police car appear in your rearview mirror, and you're asked to step out for a field sobriety test, a cocktail of emotions may stir within you—from anxiety to trepidation. But before you step out onto that precarious roadside 'stage,' it's essential to understand which field sobriety tests hold water in the eyes of the law and which may be less scientifically backed.

The Standard Sobriety Tests: A Closer Look

Field sobriety tests (FSTs) are used by law enforcement to determine if a driver is impaired. While there are various tests that officers might employ, not all are created equal, and not all are considered reliable indicators of impairment. Let's explore the science and validity behind the most common FSTs.

1. Horizontal Gaze Nystagmus (HGN)

The HGN test involves an officer observing a person's eyes as they slowly move a pen or another object horizontally in front of them. It could signify impairment if the person’s eyes involuntarily jerk or cannot follow the object smoothly. The National Highway Traffic Safety Administration (NHTSA) deems the HGN test as the most accurate FST, with correct impairment indications 77% of the time.

2. Walk-and-Turn (WAT)

During the WAT test, an individual is asked to walk nine steps heel-to-toe along a straight line, turn on one foot, and return similarly. Officers look for signs of impairment such as an inability to maintain balance, starting before instructions are finished, stopping while walking, not touching heel-to-toe, stepping off the line, using arms to balance, taking the wrong number of steps, or making an improper turn. This test is reported to have an accuracy of around 68%.

3. One-Leg Stand (OLS)

In the OLS test, a person is instructed to stand with one foot approximately six inches off the ground and count aloud until told to put their foot down. Indicators of impairment include swaying, using arms to balance, hopping, or putting the foot down early. The NHTSA suggests this test has an accuracy rate of about 65%.

Challenges to Field Sobriety Test Validity

While these tests are standardized and backed by the NHTSA, the accuracy rates are not foolproof. Factors such as the test conditions, individual officer biases, the subject's nervousness, physical conditions, or even footwear can all affect the results. Furthermore, drivers are not legally required to submit to FSTs in most states, and the performance on these tests can be subjective. It's worth noting that refusing to take a field sobriety test can have varying legal consequences depending on the state.

When Science and Law Intersect

The reliability of FSTs has consistently been controversial in scientific circles and courtrooms. Legal challenges often arise from questions about the administration of these tests and their subjective nature. Scientific critiques stem from lacking empirical evidence supporting the tests' asserted accuracy rates.

Beyond Field Sobriety Tests

It's important to mention that FSTs are typically just one component of a DUI investigation. Chemical tests, such as breathalyzers and blood tests, are more definitive means of determining blood alcohol content and are more challenging to refute in court.

St. Augustine DUI and Driving Offense Lawyers

If you or someone you know is facing charges related to a field sobriety test in Saint Augustine, FL, it is crucial to have experienced legal representation. At Canan Law, we understand the nuances of DUI/DWI laws and the science behind field sobriety testing. Our team is dedicated to ensuring that your rights are protected and that you receive a fair trial. Contact us today at (904) 849-2266 to discuss your case and explore your legal options. Remember, the right legal team can make all the difference in the outcome of your case.


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