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Field Sobriety Tests in DUI Arrests

The National Highway Transportation Safety Administration (NHTSA) provides a standardized model for field sobriety testing.

Not all states or local law enforcement agencies mandate the use of these standardized procedures, but the NHTSA field sobriety tests can create a point of attack for DUI attorneys in cases where these procedures are not followed.

In most states field sobriety tests are not mandatory and you have the right to refuse them.

If you have already participated in field sobriety testing, the results may be subject to challenge if the tests weren’t conducted properly-and field sobriety testing allows a lot of room for error and subjectivity.
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The NHTSA model requires the administration of three field sobriety tests.

The One Leg Stand Test

The NHTSA procedures for administering the One-Leg-Stand Test require that the officer:

  • Instruct the suspect to stand with his feet together and arms down at his sides, and demonstrate
  • Tell the suspect not to begin until he’s told
  • Ask the suspect whether he understands the instructions
  • Explain that when the suspect is told to begin, he must raise one leg approximately six inches off the ground with the toe pointed out and hold the position while counting out loud for thirty seconds saying, “One thousand and one, one thousand and two…” (and demonstrate the position)
  • Remind suspect that he must keep his arms at his sides and keep watching his raised foot
  • Ask the suspect whether he understands and wait for a response
  • Tell suspect to begin the test
  • Observe the test from three feet away and remain as motionless as possible
  • If the suspect puts his foot down, tell him to pick it up again and resume counting from where he left off
  • If the suspect counts too slowly, end the test after thirty seconds; if he counts very quickly, instruct him to continue until told to stop

The Horizontal Gaze Nystagmus (HGN) Sobriety Test

Testing procedures require that the officer:

  • Instruct the suspect that he’s going to check his eyes, that he must keep his head still and follow the object only with his eyes, and that he must focus on the object until told to stop
  • Hold the stimulus 12-15 inches from the suspect’s nose and slightly above eye level
  • Move the stimulus smoothly across the suspect’s entire field of vision
  • Check to see if the eyes are tracking together
  • Check to see whether both pupils are the same size
  • Start with the left eye and move the stimulus smoothly to the right so that it takes about two seconds to bring the suspect’s eye as far to the side as it can go. Repeat from right to left
  • Check at least twice for each of the three clues in each eye: lack of smooth pursuit; distinct nystagmus when eye is directed to the outside of field of vision (where no white is showing at the side of the eye) for four seconds; onset of nystagmus before the eye has moved 45 degrees

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The Walk and Turn (WAT) DUI Test

The officer administering the test must:

  • Instruct the suspect to place his left foot on the line and his right foot heel-to-toe in front of it, and demonstrate
  • Confirm that the suspect understands that this position must be maintained while the instructions are relayed
  • If the suspect breaks position during the instructions, stop the instructions until the suspect is back in position
  • Tell the suspect not to begin until he is instructed
  • Tell the suspect that he will be required to take nine heel-to-toe steps down the line, turn around, and take nine steps back down the line
  • Demonstrate two or three heel-to-toe steps
  • Instruct the suspect to keep both arms at his sides, watch his feet, count the steps out loud, and not to stop walking until the test is complete
  • Ask the suspect whether he understands the directions
  • If the suspect indicates that he does not understand the instructions, repeat the part that he does not understand, but not the entire instructions
  • Tell the suspect to begin, and that he should count his first step from the heel-to-toe position as one
  • If the suspect staggers, steps off the line, stops or stumbles, have him resume from the point of interruption

NHTA Says Officer Should Give You All Three Tests to Determine Impairment

NHTSA data clearly indicates that the accuracy of field sobriety testing declines dramatically when only one or two of these tests are performed.

The model depends on the use of all three tests, and on strict procedures being followed for the administration of each test.

Even when all three tests are used in conjunction and administered according to NHTSA procedures, assessments are accurate in only 91% of cases.

And, of course, many field sobriety test administrations are not conducted perfectly.

DUI Lawyers Can Fight Test Results

Field sobriety tests are primarily intended as a tool for officers to determine whether or not further action is required, and in those cases aren’t likely to have a significant impact on the outcome of the case.

However, in those cases in which field sobriety test results are critical to the prosecution, either because of a low BAC or because the BAC test wasn’t properly administered, deviation from the NHTSA guidelines may provide the weak point at which a DUI lawyer can successfully defend you against a DUI charge.

If you need more information on field sobriety tests, speak with a DUI attorney.

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The DUI attorneys within the Total Lawyers network can assist you with questions concerning the significance of field sobriety tests in a court of law.