Standardized Field Sobriety Tests

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Shortly after the initial contact with a suspected intoxicated driver the police officer will have the driver exit the vehicle for the purpose of performing a series of tests designed to provide “proof of intoxication”.   These tests serve two functions:  (1) they provide the officer with the probable cause necessary to make an arrest and transport the suspect for a BAC test and (2) they provide the officer with evidence of intoxication to be used in the event the suspect refuses to take the BAC test at the jail.  Obviously, neither of these functions serve the suspect’s best interest.  My friendly advice–NEVER PERFORM ANY FIELD SOBRIETY TESTS in any form.  You are not required under any statute to take any of the officer’s field sobriety tests, so why would you ever give him more help with his case against you than you are required to provide.  Do not misunderstand, you ARE required to submit to a BAC test by blood, breath, or urine, but only by methods prescribed by the Arkansas Department of Health, which I assure you will not take place on the roadside.  You simply don’t have to jump through all the hoops like a circus animal on display for the officer.

The standard battery of tests are the Standardized Field Sobriety Tests.  This series of three tests is performed in the exact same manner and with the exact same standards in every state and by all police agencies.  The battery of tests is composed of the Horizontal Gaze Nystagmus (HGN), the Walk and Turn (W & T), and the One Leg Stand (OLS).  Officers often attempt to utilize other non-standardized tests such as reciting the alphabet, counting backwards (numbers), Romberg balance test, finger dexterity drills, and so on.  None of these “other” tests are standardized; therefore, there aren’t any proscribed errors or error rates which can be relied upon to successfully predict intoxication.  Thereby, the best rule–NEVER PERFORM ANY FIELD SOBRIETY TESTS in any form.  You will be surprised at how many highly educated people cannot correctly recite the alphabet while under the influence of small amounts of alcohol combined with the stress of a DWI investigation.

Horizontal Gaze Nystagmus (HGN)–nystagmus is the involuntary “twitching” or “jerking” of the eyes.  Nystagmus is a naturally occurring condition.  Alcohol and drug consumption does not create nystagmus, but will often exaggerate and amplify the condition.  While tracking a moving object, most person’s eyes will follow the object in a smooth, fluid motion as the object moves across the person’s field of vision.  A person experiencing nystagmus will not demonstrate this smooth tracking across the field of vision, but the eye will move in rapid jerking motions across the field.  This “twitching” is visible to the naked eye and is the “evidence” the officer is looking for during his tests.

There are six prescribed clues that a trained officer will be looking for during the testing (3 for each eye):  (1) lack of smooth pursuit, (2) distinct and sustained nystagmus at maximum deviation, and (3) onset of nystagmus prior to an angle of 45 degrees.  Observation of 4 of 6 clues (or more) indicates a BAC of 0.08% or higher.  Additionally, the officer will be looking for equal pupil size, equal tracking for both eyes, and vertical nystagmus.   You have absolutely no control over this condition and you cannot feel or perceive the condition.  The detection is completely subjective and is very difficult (if not impossible) to disprove.  NEVER PERFORM ANY FIELD SOBRIETY TESTS in any form.

There are other environmental and neurological conditions that cause nystagmus.  I’m not a medical doctor or an optometrist, so I’m not going to pretend to discuss the medical causes for nystagmus with the exception of stating that they do exist.  In my experience as a former police officer, Certified Law Enforcement Instructor, Certified Drug Recognition Expert, and criminal defense attorney,  the most common error made during the administration of the HGN test in the field is the failure of the police officer to eliminate all potential source of opto-kinetic nystagmus.  This is nystagmus induced by an object repeatedly and rapidly moving across and off the person’s field of vision.  Examples frequently encountered during a DWI investigation are the flashing lights on the officer’s vehicle, the headlights of the passing motorists on the roadway, the movements of flashlights of other officers, and the reflections of the police lights on nearby windows and traffic signs.  Any or all of these are often present during the administration of a HGN test.  Any of these can cause nystagmus, which is detectable by the police officer.  The problem–the officer is not trained to distinguish between horizontal gaze nystagmus and opto-kinetic nystagmus.  So anything he sees–he will call nystagmus.  Of course, he’s not going to mention in his reports or his testimony that the nystagmus he observed might be opto-kinetic nystagmus and not HGN.  But if you remember only one thing from this blog, it should be this:  NEVER PERFORM ANY FIELD SOBRIETY TESTS in any form.

But if you’re that person that simply can’t refuse to do something a police officer tells you to do, this is where a trained and educated attorney can be worth the money expended to fight a DWI.  An informed and prepared attorney can utilize the officer’s training manuals and education to point out the potential sources of opto-kinetic (or medical) nystagmus.  In my opinion, it’s fairly easy to wipe out the validity of the HGN test in most DWI trials, as most officers don’t take the time or make the effort to eliminate the potential sources of error before administering the HGN test.

Next time, I’ll continue with the Walk and Turn and One Leg Stand.  Be careful, stay safe, and remember the best way to beat a DWI is to never get behind the wheel after drinking.

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