Welcome back to the second installment of my 10-part series on Standard Field Sobriety Tests.  I am defense attorney, Leon Matchin, and I want to share some factual information with you about what SFST’s are.  If you missed last week’s blog on Part I: HGN, you can find it here.

Last time, we talked about horizontal gaze nystagmus (HGN) and the basics of how the police administer this test.  Today we’re taking a look at optical medical conditions related to nystagmus that could affect the accuracy of their methods.

If the suspect has what is known as the lazy eye condition, the officer is trained to test one eye while the other eye is covered by the suspect’s hand, then to switch same.  A person who is color blind is not validated for this test as they will probably have a pathological nystagmus which is normal and natural for that person.

Three to four percent of the general population will exhibit a pathological nystagmus. This can be caused by some type of neurological disorder, brain damage, epilepsy or pathological disorder which the suspect is born with or of unknown etiology.  A large disparity between the right and left eye can clue the officer into this problem.

At an accident scene, if the suspect sustains a concussion, this may bring on a pathological nystagmus thereby invalidating this test.  Although very few test conditions affect gaze nystagmus, there are certain administrative procedures that must be followed.

As previously mentioned in the last blog, the stimulus must be placed twelve to fifteen inches in front of the suspect’s eyes.  The stimulus should be held above eye level, so that the eyes are wide open when they look directly at it.  Due to the narrowness of certain individuals’ eyes, it becomes more difficult to make a fair evaluation of the nystagmus unless the eyes are open wider than some can naturally perform.

If the officer believes that the nystagmus might be there, it cannot be scored, as the benefit of the doubt must be given to the person that is being tested.  The officer is also trained to administer this test with the suspect looking into a quiet background, away from the police cruisers overhead lights.  This is to avoid the probability of evaluating an induced condition known as opto-kinetic nystagmus, which is brought on when a person focuses on several objects at one time or on objects that are moving away.

Opto-kinetic nystagmus is a defense mechanism of the body in order to keep the eyes from tiring.  As such, there are numerous visual or other distractions that may impede this test.  Certain environmental factors such as wind, dust, etc. may interfere with the performance of the Nystagmus test.

If you’ve failed the SFSTs because of an eye condition, call me, attorney Leon Matchin, immediately at (833) 732-7320 to fight your DUI/DWI charge.

This leads us to our next part of the Standard Field Sobriety Tests, Part III: Optical Intoxication Signs where we will delve into the optical signs law enforcement look for to validate their claims of compromised sobriety.

Come visit me next week to learn more!