South Carolina law enforcement officers rely on the field sobriety tests to gauge a driver’s ability to safely pilot the vehicle. While departments often rely on other tests to gain a clear understanding of the driver’s ability, the National Highway Traffic Safety Administration (NHTSA) promotes the training and administration of three specific tests designed to indicate a driver’s impaired status.
The three standardized tests are the horizontal gaze nystagmus test, the walk-and-turn test and the one-leg stand test. Even though these tests are considered standard, and the officers follow a specific set of criteria, there are numerous problems with the accuracy of each field sobriety test, including:
- Horizontal gaze nystagmus is a test that measures the jerking motion of the eyes as they follow a moving object. The expectation is that when an individual consumes alcohol, this jerking motion is more visible. Unfortunately, the driver might struggle with a medical condition that exaggerates the motion of the eyes. Additionally, this test is subjective, meaning that there is no objective measure for what the officer considers a “normal” level of eye movement.
- Walk-and-turn is a straightforward test where the officer instructs the driver to take nine heel-to-toe steps in a straight line, turn, and come back the same way. Unfortunately, the driver might suffer from a medical condition such as an inner-ear infection that could impact his or her coordination. Additionally, the test might occur across uneven pavement. Passing traffic might create a distraction. Any of these situations could impact balance, coordination and the ability to follow the officer’s instructions.
- One-leg stand is a field sobriety test where the officer instructs the driver to remain steady while standing with one foot lifted six inches off the ground. Like the previous example, a medical condition might impact the driver’s balance and coordination during this test. Additionally, passing traffic or new, clumsy footwear could impact balance.
While law enforcement officers consider these three tests standard, they are far from perfect. The results are highly subjective, relying on the law enforcement officer’s observation and perception of events. Numerous factors can influence the driver’s ability to complete these tests. From taking legally prescribed medication to standing close to a busy highway, drivers might have trouble completing these tests.