Field Sobriety Tests


     At the scene of the arrest, and before you were placed under arrest, a police officer may have requested you to perform a field sobriety test ("FST").  An FST usually has three standard components:


   1.    A horizontal gaze nystagmus test;


   2.    A walk and turn test; and


   3.    A one leg stand test.


   All three standard components of the FST are intended to provide the police officer who is administering and interpreting the test with:


1.    Information that will help the police officer to determine whether the suspect is under  the influence of intoxicating liquor; and


2.    Evidence to use against the suspect in a criminal case and/or ADLRO case.


   The police may have asked you to perform other types of FSTs (e.g. an arched back test, saying the alphabet backwards, touching the tip of your finger to the tip of your nose while your eyes were closed, etc.).  However, the standardized field sobriety testing protocol established by the National Highway Traffic Safety Administration ("NHTSA"), and the HPD's current standard training procedures, call for the use of the three components listed above when an FST is administered.


   All three components of the FST are designed to test the suspect's ability to remember, and to follow, instructions.  The walk and turn test, and the one leg stand test, are also designed to test the suspect's balance and coordination.  The horizontal gaze nystagmus test ("HGN test") is designed to detect a phenomena called "nystagmus".  Nystagmus is an involuntary jerking of at least one of the eyeballs.  Nystagmus can be caused by the consumption of alcohol.  However, as will be explained below, it can also be caused by many other things which have nothing whatsoever to do with the consumption of alcohol.


    Similarly, there are many factors other than the consumption of alcohol that impair performance on a walk and turn test and/or a one leg stand test (e.g. fatigue; nervousness; misunderstanding of instructions - as opposed to an inability to remember and follow instructions because the suspect is drunk; inappropriate footwear including rubber slippers and high heels; wind; a sloped surface etc.)  

Some people also have difficulty with balance even when sober.  


    It is a crime to drive under the influence of intoxicating liquor.  It is not a crime to be uncoordinated, to have a poor memory or to be someone who is not good at following instructions.  One of the problems with all of the components of the FST is that they lack specificity.  They are overinclusive.  The innocent, as well as the guilty, can fail the tests.


     For more information about how each component of the FST should be administered, interpreted and scored, click on the links below:


2013 NHTSA Manual

2013 NHTSA ARIDE Manual:

Advanced Roadside Impaired

Driving Enforcement

Contact Mr. Mac Master immediately for a free telephone consultation


(808) 531-8080


fax: (808) 531-4044


send e-mail to Mr. Mac Master at

The information in this website is provided as a public service. It is not intended to be given to, or taken by, any individual or organization as legal advice specifically for that individual or organization. Merely viewing this website does not create an attorney-client relationship with Mr. Mac Master. Any individual who has been arrested for DUI, or any other criminal offense, or cited for any violation, is hereby requested to contact Mr. Mac Master, or another duly licensed attorney, to seek legal advice applicable to the unique facts and circumstances of that individual's situation.