HGN and Driving Impairment

Maryland vs. Brightful et al.

In pondering how to address the questions and issues raised by Judge Galloway in the recent Maryland DRE case (Maryland vs. Brightful et al), I came to the realization that Judge Galloway didn't identify any new issues. I have been asked questions about these very issues in past cases and hearings, including "Frye," "Daubert," and similar hearings. Thus, I will try to comment as I have (and will) in court. Of course, witnesses aren't allowed to give a speech in court; rather witnesses answer questions. But sometimes, the questions are so broad that they require a fairly lengthy narrative.



To illustrate, my two favorite questions - questions I have actually been asked - required lengthy answers. Question 1: "What are the drugs of abuse and what are their effects?" Anticipating an objection by the defense ("Objection, calls for a narrative"), I paused before answering. When no objection was raised, I asked the judge if I could use write on the court's whiteboard. "Go right ahead" said the Judge. I put on a mini-DRE course! Took about an hour. Question 2: "What procedure do you use to determine if an individual is under the influence of drugs?" Again, with the judge's permission, I wrote out the 12 step procedure, explaining step by step. Even explained the so-called "normal ranges" of pupil size and vital signs. Again, I put on a mini-DRE course.



(As an aside, my least favorite question was asked by a defense attorney, again in a DRE admissibility hearing: "Now these 7 categories of drugs you just talked about...is this a list of the drugs you personally have abused?" When the prosecutor didn't object but giggled instead, I tuned to the judge and very politely said, "Your honor, can I object?" The judge replied, "No, but I will." Obviously, the defense attorney insulted me in an attempt to goad me into losing my cool. It didn't work.)



In court, the expert witness, such as a DRE, is a teacher. And the best teachers, whether in college, the police academy, or DRE school, make the complicated simple and understandable. They explain rather than dictate. (The best teachers also know how to pronounce and spell the words of their profession!)



The issue of HGN and driving impairment was brought up in the Maryland case. In my opinion, HGN, in the person who doesn't have it naturally (I've seen 2 people with HGN unrelated to alcohol or drug use.), is a temporary dysfunction of the person's visual tracking system. As we know, the sober person's eyes normally track smoothly from side to side without any visible jerking. But how does this relate to driving? This is how I generally have explained it in court.

In order to properly conduct the Horizontal Gaze Nystagmus test, the subject is admonished to not move his/her head while following the stimulus as it moves from side to side. Although it varies from person to person, in my experience, most people at a .15 BAC are not able to deviate their eyes and keep their head fixed. Their eyes move and their head follows. In order to compensate for this, we may have the person hold his/her chin with the hands, put the back of his/her head against a wall, or even hold a flashlight under the person's chin to keep it from moving. Usually, these measures are unsuccessful. The person just can't move the eyes without moving his/her head. As the alcohol level goes up, the angle at which the person moves his head, in effect to catch up with the eyes, occurs earlier.

In everyday conversation, people move their eyes about 45 degrees. Imagine two officers talking to a citizen. The citizen doesn't move his/her head like a bobble-head doll, or an infant for that matter, from one officer to the other. The citizen moves his eyes. Beyond 45 degrees, however, the person moves his head. If the person can't deviate the eyes 45 degrees before moving the head, there's a good chance that person is under the influence of alcohol or other nystagmus-causing drug. And SFST practitioners know the significance of the 45 degree angle.

Obviously, a person needs to see in order to drive. Furthermore, a driver needs to be able to keep the vehicle in the proper lane while being aware of hazards, other vehicles, exits, etc. that may intrude on the roadway. The driver (at least the sober one) continually moves his/her eyes and head from side to side while maintaining proper lane position, speed, distance from other vehicles and more. Truly, driving is a divided attention task.

The alcohol and/or drug-impaired driver has a decreased ability to divide and shift attention from one thing to other. We certainly assess this impaired divided attention when we administer the Standardized Field Sobriety Tests, including HGN. As I discussed a few paragraphs ago, a person with HGN has a decreased ability to keep his/her head facing forward while looking (gazing) to the side. As a result, the person turns his/her head. In effect, the person looks to the side. If the person is driving, and his/her attention is distracted from the road by, for instance, a police officer conducting an enforcement stop, the driver will look to the side. After all, that's why police cars have high visibility lighting - to get someone's attention.

It's a basic principle of motorcycle operator training that you should "look where you want to go." The converse of this is that you will "go where you are looking." So, to avoid a road hazard, motorcycle riders are taught to look for the safe route around the road hazard. Again, look where you want to go, not at what you are trying to avoid. This principle applies to cars, trucks, and even bicycles. This principle also applies to sober as well as impaired drivers.

Sober drivers, however, are usually able to maintain proper lane position while quickly looking to the side. In fact, the sober driver may not move his/her head, but just the eyes. On the other hand the impaired driver - the driver with alcohol and/or drug induced HGN - may not be able to move the eyes to the side while keeping the head straight. The impaired driver may turn his/her head to the side, and drive in that direction. Again, the impaired driver may "go" where he/she is looking. And too frequently, this results in the impaired driver driving into an existing crash investigation, or a police vehicle with lights flashing. You go where you look.