A routine element of many DWI traffic stops in Texas is the Standardized Field Sobriety Test (SFST), in which a police officer instructs a person suspected of drunk driving to perform a number of physical tasks. Most field sobriety tests involve three elements:
- Standing on one leg: The one-leg stand test requires the driver to raise his or her leg six inches off the ground and hold it for approximately 30 seconds.
- Walking and turning: In this portion of the test, the driver must take several steps, heel to toe, along a straight line, and then return along the same path.
- Horizontal gaze nystagmus test: In this test, the police officer holds an object (typically a pen or a small light) in front of the driver’s eyes and instructs the driver to track the object’s movement. Involuntary eye movements (nystagmus) made during this exercise may be a sign of impairment.
While field sobriety tests can indeed provide evidence of drunk driving, there are many reasons a perfectly sober person might fail them.
A physical condition may cause you to fail
It takes good balance and muscle control to stand on one leg for 30 seconds or to walk heel-to-toe in a straight line without deviating from the path or raising your arms to maintain balance. People suffering from recent injuries, inner ear infections, vertigo and other medical conditions may find it impossible to achieve this level of balance.
Certain eye impairments and neurological conditions may make it impossible to pass the horizontal gaze portion of the test. Cataracts and Multiple Sclerosis, for instance, are known to cause the same type of eye movements that are associated with intoxication.
This is only a brief synopsis of some of the reasons people may fail the field sobriety test. Other examples include broken bones, head injuries and difficulty hearing the instructions. Even something as commonplace as obesity may make it difficult to perform these physical feats.
A failed test does not mean you were intoxicated
Could a sober person fail field sobriety tests? The answer is an unequivocal yes. If you have been pulled over and failed to perform these physical tasks, do not lose heart. This is not proof that you were driving while intoxicated. A good defense strategy will account for other reasons you may have failed these challenging physical activities.
