Horizontal Gaze

Interviewer: So what is the horizontal gaze test?

Court Koehler: Yeah. There are three tests. These are the only three tests the NHTSA has approved that an officer is supposed to use. Sometimes there are some auxiliary tests they’ll use such as the alphabet test; everybody knows that one. Then there is the touch-your-finger-to-your-nose test. Those really not supposed to be used. They’re not necessarily validated by the studies that NHTSA has done. Sometimes they do them if, for some reason, they’re not able to do the other tests. If someone has an injury or something like that, then they’ll do those other tests.

But these three that we’re talking about are the only three that are really validated by any kind of studies or science. So there’s the Horizontal Gaze Nystagmus. Nystagmus is kind of when your eye bounces or moves a little bit. Some people can have it as a medical condition for whatever reason. Their eyes just kind of bounce; you may have met somebody that has that. The theory is that when you are intoxicated, your eyes will have that nystagmus where they’re bouncing.

What they do is, the officer will have you look at usually a penlight or the tip of a pen or something like that and they will move the pen back and forth across your field of vision. They’re supposed to be about a foot to two feet away from the front of your eyes. They do this a few different times and they do it for different lengths. What they’re doing is, first of all they’re looking for equal tracking in people’s eyes, is what they say. So if your eyes aren’t tracking the pen properly or your pupils are different sizes, then that’s an indication that there’s something neurologically wrong.

If you hit your head, or if you might have had a stroke or something like that, that’s a problem they need to maybe call an ambulance or something like that. So if you have equal tracking and equal pupil size, then you pass that first gate and then they go on with checking for the nystagmus. The first thing they do is they look for stationary nystagmus. They’re just looking at your eyes when you’re not following the penlight. They’re just checking to see if there’s any of that bouncing in your eyes.

Then they look at each eye and they look for a nystagmus as you’re following the penlight, and at the farthest edges of the light. They’ll do it up to forty-five degrees first. If you have the nystagmus during that initial phase of where you see the nystagmus in the eyes – in between those forty-five degree angles, right in front of your face – then that’s another clue and they go on further out from each side. Then they’re looking for nystagmus past that forty-five degree angle, so out over in the sort of more peripheral area of your vision.

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The clues in this are the lack of smooth pursuit of the eyes, meaning you have a nystagmus while the penlight is moving back and forth, or if your eyes are bouncing and not tracking the penlight the right way. Then they’re looking for the nystagmus out to a forty-five degree angle and then out past that, kind of at the maximum edges of your vision there. Also, sometimes they’ll check for vertical nystagmus as well. So they’ll move the pen up and down.

Out of all them, this is sort of the more objective of the tests. You’re going to have a nystagmus or not. As long as the officer does things the right way in terms of having the penlight the right distance, and having it out to the right angles of your vision, then it should be pretty objective. The problem is lots of people can have nystagmus for different reasons that don’t have anything to do with their being intoxicated. Lots of medical conditions can cause it. You can have it just in general, normally. So it’s not necessarily reliable for that reason.

At least it sort of relies on some kind of objective measures, more so than just listening to instructions for your Walk-and-Turn and your One-Leg Stand test.

Interviewer: When they’re doing the Horizontal Gaze, is the person going to be sitting down or is that person going to be standing up when that’s happening?

Court Koehler: Theoretically they should be out of their car, standing up. The officer is supposed to turn any kind of distracting headlights away. Maybe turn the overhead flashing lights off of their car, or down to sort of the warning level so that you don’t have a lot of visual distraction going on. What you see in practicality though, is this is a lot of times the first test that they do. Sometimes you’ll see an officer come up to the side of the car and if he thinks that you’re driving under the influence, which means that if you’re driving out at night past ten o’clock and you make a minor traffic error, then they’re automatically suspicious that you’re driving under the influence.

So they pull out their pen while you’re sitting there in the car and they’ll just do it right there. “Have you had anything to drink?” “Oh, no I haven’t, officer.” “Okay, well why don’t you take a look at this light?” And right there you feel like you have to do that. You know that this is a field sobriety test but the officer just says, “Hey, look right here,” and you don’t realize that you don’t have to take this test. That’s one of the things they’re really good at kind of getting you to take these tests without you actually consenting to do it, or realize what you are doing.

You could be sitting in the car, and he’s already given you the Horizontal Gaze Nystagmus test right off the bat; you’ve barely even spoken to him. Theoretically you’re supposed to be out of the car, but that doesn’t necessarily always happen.

Interviewer: You mentioned that the Horizontal Gaze, the Walk-and-Turn, and the One-Leg Stand are the three main ones but I know there are a few other ones out there. For instance, I’ve heard of a coin-to-the-ground test. Have you seen that one being performed or administered?

Court Koehler: No, they really are pretty good, at least in this state, about just sticking with those three, unless there’s some sort of a problem with taking the other tests with an injury or something. The times I’ve seen them do other tests are when the driver claims that they have an injury. For instance, I had a client that had a knee surgery right before he was pulled over. So he said, “I can’t do the Walk-and-Turn test or the One-Leg Stand test.” That’s obvious and understandable. Because he couldn’t get any sort of results from that test, the officer had him do a couple of other tests. He did the alphabet test.

I’ve seen a test, too, where they have you touch your fingers to your thumbs, in a specific order. There are some things like that. There’s the finger-to-the-nose test. Occasionally you see those, but they’re really pretty good about just sticking with the three NHTSA approved tests.

By Court Koehler

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