In Texas, police officers use the so called Standardized Field Sobriety Tests when they suspect that a motorist may be intoxicated.  Typically the tests are conducted at the roadside under variable conditions; on occasion they are conducted at the police station.

     I.     The Horizontal Gaze Nystagmus (HGN) Test.

     In this test, an officer moves a stylus, frequently a pen, in front of your eyes for the purpose of determining whether nystagmus is present.  Nystagmus, generally speaking, is an involuntary jerking of the eyes.  The HGN test is divided into three parts, and police are looking for certain “clues” that nystagmus is present. 

     The police claim that if nystagmus is present, it indicates that someone is intoxicated due to the introduction of alcohol into the system.  There are several problems with this claim.  First, in order for the HGN test to have any validity at all, it must be administered in accordance with the training that the police receive.  The police are trained to conduct all the standardized field sobriety tests according to the protocol developed by the National Highway Traffic Safety Administration (NHTSA).  Secondly, nystagmus may be due to sources other than alcohol.  Third, even if properly performed, there is no scientifically valid, reliable evidence that a particular result on HGN correlates to a particular alcohol concentration.  In other words, the HGN test shows, at best, that a person may have consumed alcohol.  It cannot be used to prove a person’s alcohol concentration.  
  
         II.     The Walk and Turn

     In this test, the officer will first instruct the subject to stand in a certain position as the officer delivers a series of oral instructions that the subject is expected to remember.  Then the subject is instructed to take nine heel to toe steps on an imaginary line, then pivot as instructed and take nine heel to toes steps back.   

     In the Walk and Turn  test, like the HGN, the officer is looking for supposed clues of intoxication.  In this test, there are a possible eight clues.  Would it surprise you to learn that if, in the officer’s subjective opinion, the subject scored two clues, you have failed the test?  That is correct.  A subject may complete six of the eight portions correctly and still fail the test, according to the police.

      The Walk and Turn test is a highly subjective test that must be administered in accordance with NHTSA training to yield a valid result.  In addition, like the HGN, it cannot be reliably correlated to a specific alcohol concentration.  In other words, even if you “fail” the Walk and Turn test, it does not prove a specific alcohol concentration.

     III.     The One Leg Stand

     The final test in the battery of standardized field sobriety tests is the One Leg Stand.  In this test, the officer asks a person to stand on one leg while counting.  The police officer is looking to see if the person can maintain this position for thirty seconds without placing their leg on the ground.  Frequently, the police do not inform the subject of the length of time they are expected to maintain their leg in the air. 

     On this test, the officer is judging a person’s performance on four clues.  The police consider a score of two or more clues a failure.  

     The police may also ask you to engage in one or more non standardized tests such as reading from a document, reciting the alphabet, or performing the Rhomberg test.

   Derk Wadas is a DWI lawyer serving Plano, Frisco, McKinney and all of Collin County Texas through the law firm Wadas Law Office.

 

 

 

In Texas, police officers use the so called Standardized Field Sobriety Tests when they suspect that a motorist may be intoxicated.  Typically the tests are conducted at the roadside under variable conditions; on occasion they are conducted at the police station.

     I.     The Horizontal Gaze Nystagmus (HGN) Test.

     In this test, an officer moves a stylus, frequently a pen, in front of your eyes for the purpose of determining whether nystagmus is present.  Nystagmus, generally speaking, is an involuntary jerking of the eyes.  The HGN test is divided into three parts, and police are looking for certain “clues” that nystagmus is present. 

     The police claim that if nystagmus is present, it indicates that someone is intoxicated due to the introduction of alcohol into the system.  There are several problems with this claim.  First, in order for the HGN test to have any validity at all, it must be administered in accordance with the training that the police receive.  The police are trained to conduct all the standardized field sobriety tests according to the protocol developed by the National Highway Traffic Safety Administration (NHTSA).  Secondly, nystagmus may be due to sources other than alcohol.  Third, even if properly performed, there is no scientifically valid, reliable evidence that a particular result on HGN correlates to a particular alcohol concentration.  In other words, the HGN test shows, at best, that a person may have consumed alcohol.  It cannot be used to prove a person’s alcohol concentration.  
  
         II.     The Walk and Turn

     In this test, the officer will first instruct the subject to stand in a certain position as the officer delivers a series of oral instructions that the subject is expected to remember.  Then the subject is instructed to take nine heel to toe steps on an imaginary line, then pivot as instructed and take nine heel to toes steps back.   

     In the Walk and Turn  test, like the HGN, the officer is looking for supposed clues of intoxication.  In this test, there are a possible eight clues.  Would it surprise you to learn that if, in the officer’s subjective opinion, the subject scored two clues, you have failed the test?  That is correct.  A subject may complete six of the eight portions correctly and still fail the test, according to the police.

      The Walk and Turn test is a highly subjective test that must be administered in accordance with NHTSA training to yield a valid result.  In addition, like the HGN, it cannot be reliably correlated to a specific alcohol concentration.  In other words, even if you “fail” the Walk and Turn test, it does not prove a specific alcohol concentration.

     III.     The One Leg Stand

     The final test in the battery of standardized field sobriety tests is the One Leg Stand.  In this test, the officer asks a person to stand on one leg while counting.  The police officer is looking to see if the person can maintain this position for thirty seconds without placing their leg on the ground.  Frequently, the police do not inform the subject of the length of time they are expected to maintain their leg in the air. 

     On this test, the officer is judging a person’s performance on four clues.  The police consider a score of two or more clues a failure.  

     The police may also ask you to engage in one or more non standardized tests such as reading from a document, reciting the alphabet, or performing the Rhomberg test.

   Derk Wadas is a DWI lawyer serving Plano, Frisco, McKinney and all of Collin County Texas through the law firm Wadas Law Office.