Driving While Intoxicated – Part I

Using Gait Analysis and Medical History for DWI Defense
By: Evan Levow and Paul Greenberg

It is not illegal to drink and drive. It is however, illegal to drink an amount of alcohol that causes one to become impaired or above the legal “per se” limit. As such, a great deal of evidence admitted in a DWI case is based upon a police officer’s opinion that the suspect’s driving ability is impaired by alcohol. A DWI arrest is mostly based on subjective assessments made by the arresting officer, where the accused is often left defending a “he said, he said” situation. The officer describes the individual’s driving behavior, the interaction roadside, the arrest, the ride back to the station or hospital, and the breath or blood testing factors. To mount a successful defense, the motorist must refute these subjective opinions.

In reaching the decision to arrest, the officer often relies upon physical roadside “testing” to assess the drivers’s sobriety. Most of these “tests” are based on a series of field studies commissioned by the National Highway Traffic Safety Administration (NHTSA), NHTSA recommends a three-test battery for use by law enforcement to assess whether a driver is under the influence of alcohol. The NGTSA Standardized Field Sobriety Tests (SFSTs) include the Horizontal Gaze Nystagmus (HGN), Walk-and Turn (WAT) , and One-Leg-Stand (OLS). This three-test battery has been used by law enforcement in the United States since the mid-1970s. NHTSA asserts that these test are sound because they are both “standardized” and “Validated.”

These “tests” have been used in the medica setting, and it was thought that they mav have application for DWI assessment. This is not entirely implausible, as alcohol intoxication is a neurological dysfunction and has certain symptoms that might be measured by physical tests, This does not mean, however, that minimally trained police officers can accurately diagnose alcohol intoxication by the side of the road, in poor lightning, with a nervous subject, with no access to the subject’s medical history and with these crude tests. Yet, this is what is done on a daily basis.

The OLS and WAT are divided attention tasks.’ That is, they require subjects to divide their attention between a mental task (remembering and following instructions) and a physical task (balancing). Horizontal Gaze Nystagmus and Vertical Gaze Nystagmus are not divided attention tasks, but rather they show an involuntary muscle movement in the eyes that can be exaggerated by alcohol consumption . The SFSTs are not a measure of one’s ability to drive. They are alleged to correlate to a percentage likelihood that a person is at or above a specific blood alcohol level. Consider also that a horizontal gaze nystagmus test is not alcohol specific there are many other causes of visible nystagmus other than alcohol consumption. Similarly, gait analysis can reveal that clues observed on the balancing tests are similarly not alcohol-specific.

A DWI attorney must be familiar with the SFST statistics and the clues the officer used to assess the driver. Cross-examination often focuses on whether the officer gave proper instructions during the testing and whether someone properly recorded and interpreted the results. Rather than merely presenting a contrarian defense by seeking to discredit the officer’s subjective assessment, it is preferable to remove the subjectivity as much as possible and offer alternative explanations of the behaviors interpreted by the officer.

Unsteadiness is among the most common indicators of impairment recounted by police officers in a DWI case, whether it is related to a person’s walk or related to an SFST. During the initial intake meeting with the client, a medical history should be obtained, inquiring as to whether any physiological factors may have affected behavior overall at the time of the arrest, but specifically, whether any inquiry or pathology would have accused behavior overall at the time of the arrest, but specifically, whether any injury or pathology would have caused any problems in balancing. Clients often respond that they have generally poor balance and would not be able to perform those exercises mid-morning in a gym, much less roadside with varying temperatures, slope, traffic, and flashing lights causing multiple distractions. It is therefore imperative that a client’s gait, or walking pattern, be evaluated to correlate any medical conditions or client-specific gait patterns that may explain why his gait was unstable, irregular, or inconsistent at the time of the arrest.

PART II – Posted on Monday 10/7/13

The Morales Law Firm would like to thank The National Association of Criminal Defense Lawyers Champion for sharing this information with us.