Monday, August 25, 2014

The Eyes Can't Lie: Why the DWI Eye Test is a Police Favorite

Window to the soul or revealer of drugs and alcohol

Police nationwide love one field sobriety test most of all. It is referred to as the "eye" test or the HGN or the nystagmus test. It is really the Horizontal Gaze Nystagmus test.

What is NY-stag-MUS? 

It is an involuntary jerking or oscillation of the eye ball as it tracks an object. Nystagmus is normal. Nystagmus is a natural eye condition. All eyes track and jerk BUT alcohol and some drugs can increase the jerkiness and the oscillations. It can become more apparent to the trained eye, and sometimes it so bad (severe) it can be seen by even the untrained eye.

HGN Police Sobriety Test Nystagmus is special.

The HGN police sobriety test look for nystagmus that is "distinct" and "sustained" and/or "exaggerated" and/or "magnified." 

Why is there an Increase of Nystagmus in the Eyes?

The eye balls are controlled by the eye muscles. Eye muscles are connected to nerves which go to the brain. The brain has the CNS: the central nervous system. Alcohol and other drugs affect the ability of the brain and CNS to fire off impulses to trigger proper functioning and coordinated movements.

As Alcohol levels increase so does the onset and severity of Nystagmus. Higher BACs mean more jerking and oscillations of eye movements.

HGN is the one Police Sobriety test that cannot be controlled or faked. 

Sometimes seasoned drinkers or drug users can balance, coordinate, and easily fool police testers. What they cannot fake out is the HGN test.

Nystagmus is involuntary and uncontrolled movement of the eyes.

The HGN (horizontal gaze nystagmus) test cannot be practiced or controlled. 

And that is why it is a police favorite!

Now on balance in future blog posts I will give a ton of reasons why HGN is not reliable and not accurate and not always in and of itself the best way to judge/assess impaired and/or intoxicated and/or drugged drivers. 

Always consult with an attorney about any criminal or non-criminal charges you have pending to discuss your options and/or defenses.

I am certified in Field Sobriety and Breath Alcohol Testing, and an active member of the National College of DUI Defense (NCDD). My online materials include over 500 blog posts, dozens of articles, and over 500 informative videos on my youtube channel.

I have co-authored Strategies for Defending DWI Cases in New York, in both 2011 and 2013. These are West Thomson legal manuals on New York State DWI defense, and focus on the best practices for other lawyers handling a New York DWI case. I was selected by Super Lawyers as a Upstate New York 2013 Rising Star in DWI/DUI Defense based on my experience, contributions, and professional standing.