Nystagmus: Mostly Leave It Alone

Blogging from the Rusty Duncan seminar, and listening to San Antonio DWI lawyer George Scharmen give an excellent presentation on the Field Sobriety Tests yesterday.

One interesting tidbit. Scharmen argued that while of course you must cross the officer about the 6 out of 6 (isn’t it always all 6 clues?) on the Horizontal Gaze Nystagamus, it’s not important to go on and on about it. In fact, it may give it more effect than the jury would otherwise.

Scharmen said – and my notes are skimpy here – he asks about how the officer is only trained by another officer, not a medical professional; impeaches the officer if necessary with the manual where he has made errors in administration, eg. Holding the stimulus for less than 4 seconds at maximum deviation; asks why the results weren’t reproduced for the jury by placing the subject in front of the vehicle to put the HGN on tape, and then…

“I mostly leave it alone”.

[Scharmen asks more than those 3 or 4 questions of course; he’s just saying he deemphasizes it by doing an effective short cross on it where he can.]

What is Nystagmus?

Nystagmus is an actual medical phenomenon that describes an involuntary eye movement, or ‘ a jerking of the eyes’, as police officers often call it. Nystagmus can be difficult to detect, and has multiple causes, other than alcohol consumption.

Unfortunately, diagnosing both the complex medical condition itself, as well as divining its cause, has been boiled down to a few hours of a two and a half day Field Sobriety Test certification class, and taught to police officers across Texas and the United States as the ‘gold standard’ for DWI detection.

I can’t count the number of times I have heard the phrase “the eyes don’t lie” (from prosecutors, police witnesses, and others in law enforcement). Well, the truth is that when it comes to DWI detection, they do.

This blog will attempt to dissect truth from fiction, and to study what nystagmus is, what it isn't, what causes it, and why police officers so often believe that what they saw on the scene of an arrest during a DWI investigation really isn’t science at all. Stay tuned…