Field Sobriety Testing

Field Sobriety Testing

filed sobriety lawyer

The Standardized Field Sobriety Tests (SFST) include: Horizontal Gaze Nystagmus (HGN), Walk and Turn (WAT), and One Leg Stand (OLS). The validity of the SFST results, however, is questionable in almost every case. Officers have to administer the tests exactly as trained. Any deviation can lead to invalid results. Moreover, even if administered perfectly, the tests themselves are not perfect and they are not appropriate for many individuals who have had certain past injuries, medical conditions, advanced age, etc. Our Sugar Land Criminal Attorney Knows Each Test's Flaws

Because Mr. Threadgill has been National Highway Traffic Safety Administration (NHTSA) certified in the proper administration of SFSTs, and trained regarding the many other conditions that likewise may invalidate the tests, hiring Mr. Threadgill gives you a good chance of having your SFSTs suppressed from evidence. And, even if suppression is not available, Mr. Threadgill has the tools to raise the questionable validity of the SFSTs for a jury (in the event your case is not dismissed or plead). Often, this is the key to persuading the jury that there is reasonable doubt regarding the charge brought against you.

HGN Horizontal Gaze Nystagmus

"Nystagmus" means an involuntary jerking of the eyes. HGN refers to an involuntary jerking of the eyes as they gaze toward the side. In addition to being involuntary the person experiencing the nystagmus is unaware that the jerking is happening. The theory behind the test is that nystagmus becomes readily noticeable when a person is impaired. However, Mr. Threadgill is aware of numerous other factors (aside from alcohol) that may cause noticeable nystagmus and is prepared to cross-examine state witnesses regarding same.
In administering the test the officer has the subject follow the motion of a stimulus with the eyes only. The stimulus may be the tip of a pen or penlight, an eraser on a pencil or a fingertip. As the eyes move from side to side each eye is examined for three specific clues:<>

  1. Lack of Smooth Pursuit - Does the eye move slowly or does it jerk noticeably? If there is smooth pursuit, your eye should appear as if it were a marble rolling over glass. If there is a lack of smooth pursuit, your eye should appear as if it were a marble rolling over sandpaper.
  2. Distinct Nystagmus at Maximum Deviation - When the eye moves as far to the side as possible and is kept at that position for at least four (4) seconds, does it jerk distinctly?
  3. Onset of Nystagmus Prior to 45% as the eye moves to the side - Does it start to jerk prior to a 45% angle?

WAT - Walk and Turn

The WAT is a divided attention test consisting of two stages: Instruction Stage and Walking Stage. In the instruction stage, the subject must stand with their feet in heel to toe position, keep their arms at their sides, and listen to instructions. The subject must maintain the heel to toe position and may not begin walking until all instructions are given. In the Walking Stage the subject takes nine heel to toe steps, turns in a prescribed manner, and takes nine heel to toe steps back, while counting out loud and watching their feet. Officers observe the subject's performance for eight clues:

  1. can't balance during instructions;
  2. starts too soon;
  3. stops while walking;
  4. allows more than ½ inch between heel and toe;
  5. steps off line;
  6. uses arms for balance;
  7. loses balance on turn or turns incorrectly; and
  8. takes the wrong number of steps.

A subject who exhibits two or more clues will fail the test. Scoring is entirely subjective and within the officer's discretion.

OLS - One Legged Stand

The OLS is also divided into instruction and performance stages. In the Instruction Stage, the subject must stand with feet together, keep arms at side and listen to instructions. In the Balance and Counting Stage, the subject must raise the leg of his choice approximately 6 inches off the ground, toes pointed out, keeping legs straight. While looking at the elevated foot, count out load in the following manner: "one thousand and one", "one thousand and two", etc., until told to stop. The officer will instruct the subject to stop after 30 seconds. The subject is observed for the following clues:

A subject who exhibits 2 or more clues, as determined by the officer, will fail the test.

NOTE: If you have recently been arrested for a DWI in Texas, contact an attorney immediately. You have only 15 days from the date of your arrest to contest the possible lengthy suspension of your driver's license. Fighting such a suspension may not only protect your ability to drive, but may also lead to the discovery of very valuable evidence that could assist you in winning your DWI trial.

IMPORTANT: Effective September 1, 2003: Any person convicted of driving while intoxicated will face a minimum yearly surcharge imposed by the Department of Public Safety of at least $1000.00 for the three years following conviction. Second offenders will face a yearly surcharge of $1500.00, and any person who registers in excess of .16 on a breath test and is convicted will face a $2000.00 surcharge.

  • sways while balancing;
  • uses arms to balance;
  • hops; and
  • puts foot down.