Why The Horizontal Gaze Nystagmus Test Doesn't Work (And Why You Need An Attorney)

Posted on: 4 September 2017

One of the first clues that you'll get if an officer thinks you may be inebriated is when he asks you to take a few roadside sobriety tests. One of those tests is the horizontal gaze nystagmus (HGN) test. While it sounds complicated, it's actually quite simple -- and very prone to failure. 

Here's why the HGN test shouldn't be used as the basis for a drunk driving arrest -- and why anyone charged with drunk driving after flunking it should get a DUI attorney right away:

The Test Itself Is Deeply Flawed

The government didn't particularly want to reveal its data on how well the HGN test works. When it finally did, attorneys could understand why -- even when performed under optimum conditions, on subjects who are quite physically healthy and fit, by experts that were well-trained, the HGN test indicated that as many as 77% of those tested were drunk when they were actually sober.

Compare this to a real life situation where the police officer doing the test has probably taken, at best, a few hours of training in a course that covered several different types of roadside sobriety tests, the driver is quite average and probably not nearly as fit and healthy as those used in government test studies, and the test is performed at the side of the road, possibly at night, with a bunch of cars whizzing right by.

How accurate do you imagine the test to be under those circumstances?

There Are All Sorts Of Reasons That Someone Can Fail The Test

Of all the roadside tests performed, the HGN test is considered the most scientific -- because people can't control their involuntary eye movements when they're intoxicated. That's all the officer is looking for -- a slight jump or jerkiness in the way your eyes move when you're asked to follow the officer's pen or finger as it moves first parallel to your face, then as far as you can both left and right, and, finally, from your nose at an angle out toward just about where your shoulder's end.

You only "pass" if your gaze stays perfectly smooth and doesn't jerk or jump at all, even at the edges, but here's a whole list of reasons why you can fail:

  • It's the middle of hayfever season and your allergies are acting up, making your eyes dry and hard to focus
  • You took allergy medication, which may be affecting just how well you can focus your vision, especially if it makes you a little tired
  • You're actually tired -- and like any person after a long day at work, your eyes aren't necessarily working the best
  • You're buzzed on caffeine. You might be like many other office workers and get through your day on coffee and energy drinks -- which can also affect your ability to properly focus your eyes or make you seem jumpy.
  • You have any sort of minor illness that is affecting your inner ears. Nystagmus is a test that routinely reveals everything from fluid in the ears and ear infections to migraines because any instability in the inner ear has the same effect as alcohol.

If you've been arrested on a DUI charge due to the HGN test, talk to a DUI attorney today. There are plenty of ways to show a jury that this "scientific" test is less than scientific when it comes to being an effective tool to test for sobriety.