Tuesday, June 16, 2009

Using the HGN test to your advantage

"I am going to check your eyes. Keep your head still and follow this stimulus with your eyes only. Keep following the stimulus with your eyes until I tell you to stop."

So begins the administration of the horizontal gaze nystagmus (HGN) test to the suspected drunk driver. The officer then begins the magical process of waving a pen back and forth in front of the driver's eyes to determine if he or she consumed any alcohol. Nevermind that, by that point, the driver has usually admitted to drinking "a couple" of beers or mixed drinks.

But instead of looking for signs of impairment, let's look for some signs that our driver is not impaired. Did the driver keep his or her head still? Did the driver follow the movement of the pen with his or her eyes? Was the driver standing still?

In order for the officer to administer the "test" correctly, he must be able to look into the driver's eyes. In order for him to look into the driver's eyes, the driver must be standing still and not swaying. The stance the driver takes during this test is the most normal stance he or she will take during the administration of the standardized field sobriety tests (or, as I prefer to call them, the police coordination exercises).

In order to "take" the pen and eye test, the driver must exhibit some fine motor skills. He or she must stand still and, without moving his or her head, follow an object being passed in front of the eyes. The driver must also understand the directions he or she was given by the officer - a test of mental faculties.

Think about it, if the driver can't stand still, can't keep his head still, can't follow the pen with his eyes and can't follow directions, the officer can't complete the test.

Therefore, the very fact that the officer completed the administration of the HGN test demonstrates that the driver still had the use of his or her mental and physical faculties.


Feisty said...

Paul -- excellent post. Also, sorry that I didn't see and approve your comment to my "DWN - Driving With Nystagmus" post earlier. Somehow it got lost in my cluttered inbox. I've fixed that now.

This is one of the points we intend to bring up on cross examination. The officer stated that I swayed while standing and walking (in 6 inches of snow), but also found "4 clues" in the HGN test. Chances are good that he will testify that I held my head still during that test (after all, it's the only test I took. Without the HGN, the prosecution has nothing). But that testimony will contradict the police report.

Fortunately, he also wrote in a deposition that my speech was slurred. As I recorded the arrest, and my speech sounds unimpaired, this officer will probably have a hard time on cross.

Did you get a chance to read the recent NHTSA study "The Robustness of the Horizontal Gaze Nystagmus Test"? If so, I hope you can use it in your practice, and am curious as to your response to the study. It seems to be pretty favorable to the defense.

Be well.

Paul B. Kennedy said...

Thank you for your comment. I have read the NHTSA study on the "robustness" of the HGN test and there will be a blog update devoted to it shortly.

Anonymous said...

I was administered an HGN test and the officer said I failed due to "the twitch in my eye" but I followed the pen correctly and I'm fairly certain I had no twitch. It's virtually impossible for an eye to stay completely stable with all the activity from the nervous system continuously firing impulses. Did he have a reasonable cause to say I failed the HGN test?

Paul B. Kennedy said...

The HGN test is the worst kind of junk science there is. The officer is just trained to pass a pen in front of someone's eyes and look for a twitch without regard to any cause other than alcohol ingestion.

Since the officer can't discern the actual cause of the twitching - and can't explain why the eye is twitching - the results of the test are effectively useless.

The good news is that most jurors couldn't care less about the HGN because they can't see anything.

Anonymous said...

I can explain exactly what causes the eye to jerk. It's called positional alcohol nystagmus and is only exaggerated if the person is under the influence of alcohol or certain other drugs. I would hardly call the HGN test "junk science" as NHTSA seems to think it is a pretty good test. I am a certified DRE and have done many studies on HGN and its reliability. In the last three validation studies, the three test battery, to include the HGN, is between 91 and 95 percent accurate with respects to impairment. Also whomever told you that you "failed" any of these tests is wrong. They are not pass/fail tests. You see indicators of impairment.

Curtis said...

Actually, that is incorrect. Positional alcohol nystagmus is caused by gravity creating an imbalance in the inner ear due to the head being turned off center in relation to the spine.