Missouri Field Sobriety Tests

The National Highway Transportation Safety Administration created a standardized model for field sobriety testing in 1981. The Standardized Field Sobriety Test (SFST) uses three tests in combination, and the NHTSA recommends that all law enforcement agencies use this standardized program and the associated training.

This standardized testing system – a system that NHTSA has deemed the most reliable of the available field tests – can be a DWI defense in an area where the standardized tests aren’t used.Even where the standardized test is used, there may be some errors in the test. The SFST was designed to help officers measure the appropriateness of making a DWI arrest, not as evidence to prove that a driver was intoxicated.

According to 1998 data from the NHTSA, the combination of three tests used together was only accurate in 91% of DWI cases. The arresting officer is wrong in 9 out of every 100 field sobriety tests – and those were the rates for the officers who volunteered DWI arrest records.

Not all officers who use the SFST as a preliminary DWI assessment have been properly trained to administer and interpret the test. Accurate administration of the three tests according to NHTSA procedures requires that an officer follow strict guidelines. All three tests must be administered under certain conditions.

Field Sobriety Tests – In General

These are not really tests at all; rather, I like to think of them as Roadside Agility Exercises that are highly subjective in nature, and designed for failure.In theory, these tests were designed to simulate and evaluate your “divided attention” abilities, a critical skill in operating a motor vehicle. However, there are many people who, for many innocent reasons, cannot perform these tests to the officer’s satisfaction, and pay the price with a DWI arrest.

Field Sobriety Tests – Do I have to submit to these tests/exercises?

NO! What most people don’t know is that these tests/exercises are not mandatory! However, the officer who stopped your car won’t tell you this and will use the results of the tests to justify your arrest and to accumulate evidence to be used against you in court or at the Department of Motor Vehicles. Remember, it is your right to politely refuse to accept the invitation to submit to any Roadside Agility Exercises.

Field Sobriety Tests vs. Standardized Field Sobriety Tests

In deciding whether to submit to these exercises, you should know these tests are highly subjective and only 3 have been “standardized” and “validated” as “acceptable” in the “scientific” community, while the remaining exercises are even more unreliable and unsupported as accurate for the detection of alcohol impairment.

Standardized Field Sobriety Tests Include:

Nystagmus (Horizontal and Vertical Gaze): The officer will position an object (i.e., finger, pen, etc.) 12-15 inches away from the driver’s face, and move the object from side to side while watching the subject’s eyes. The officer watches the eyes for the ability to track and/or the involuntary jerking of the eyeball. This jerking or trembling may be a sign someone has consumed alcohol. (However, Nystagmus is naturally found in a large percentage of society and can be indicative of many medical and physiological disorders)

Walk and Turn: The subject takes nine heel-to-toe steps along a line, turns, and takes nine heel-to-toe steps back. The officer is looking to see if you can follow instructions, balance, stop during the test, do not touch heel and toe, step off the line, or lose balance while turning.

One Leg Stand: The subject is instructed to stand with their heels together, arms at their side, and then told to raise one leg (your choice) six inches off the ground while counting out loud until the officer tells you to stop. Here, the officer is looking to see if you raise your arms for balance, sway, hop, or put your foot down.

Field Sobriety Tests Include: Others

Rhomberg Balance Test (also known as the Modified Position of Attention): The subject stands still with their hands at their side, feet together and then they are insturcted to closes their eyes, tilts their head back, and estimates 30 seconds. The officer is looking for problems with balance, body or eyelid tremors, if you open your eyes, swaying, muscle tension, or any other “clues” to support the officer’s subjective belief you are impaired.

Finger to Nose: The subject stands with their feet together, eyes closed, and is instructed to hold their arms to their side and alternate bringing their index finger to their nose. Here, the officer is looking to see if you sway, have body or eyelid tremors, muscle tension, or any other “clues” to support a finding of impairment.

Field Sobriety Tests include: Other Non-Standardized

  • Finger Count
  • Hand Pat
  • Alphabet Test
  • Counting Test

PAS or PBT Test: One of the most dangerous Field Sobriety Tests is the Preliminary Alcohol Screening test, also called the PAS or PBT test. This is a portable breath test whichis supposed to be used as a field sobriety test to determine the presence of alcohol. However, on the road and in a courtroom, this device is regularly used to show the content of your breath alcohol and as evidence of your guilt at hearing and in trial. It is important to understand, the officer is supposed to advise you this test is voluntary and not the one required by the Implied Consent Law, however, most of the time this is forgotten, in order to secure more evidence of your impairment and/or breath alcohol level.

Learn more about field sobriety tests:

  • One-Leg-Stand Test
  • Horizontal Gaze Nystagmus (HGN) Test
  • Walk and Turn (WAT) Test

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 feet together and arms at the sides, and demonstrate
  • Ask the suspect whether he or she understands the instructions
  • Explain and demonstrate the test –
    • Raise one leg approximately six inches off the ground with the toe pointed out
    • Hold the position while counting out loud for 30 seconds saying, “One thousand and one, one thousand and two…”
  • Remind suspect to keep arms down and keep watching the raised foot
  • Ask the suspect if he or she understands and wait for a response
  • Tell suspect to begin the test
  • Observe the test from three feet away, while not moving

If the suspect puts a foot down, the police officer will tell him or her to pick it up again and count from where he or she left off. The police officer will end the test after 30 seconds if the suspect counts too slowly, and if the suspect counts very quickly, the police officer will ask him or her to continue until to hold to stop.

The Horizontal Gaze Nystagmus (HGN) Test

The Horizontal Gaze Nystagmus test provides the most possible ground for challenge among the field sobriety tests. That’s because some DWI courts have ruled that it’s a scientific test, which requires the state to show that the officer is qualified to interpret the test and testify to the results. While the police officer is performing the field sobriety test, the suspect must keep his or her head still and follow the object with only his or her eyes, focusing on the object until told to stop. Testing procedures require that the officer:

  • 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 and if both pupils are the same size
  • Start with the left eye, moving the stimulus to the right so it takes 2 seconds to bring the suspect’s eye as far to the side as it can and repeat from right to left
  • Check at least twice for each of the three clues in each eye:
    • Lack of smooth pursuit
    • Distinct nystagmus (no white is showing on the side) when the eye is to the outside of field of vision for 4 seconds
    • Onset of nystagmus before the eye has moved 45 degrees

The Walk and Turn (WAT) Test

In addition to the requirements for officer administration, the Walk and Turn Test requires certain conditions to be administered properly. Level ground is required, along with a hard, dry, nonslippery surface. Even with optimal conditions, NHTSA indicates that the test may not be valid for the elderly, people with leg injuries or people with inner ear problems. Officers may still administer the test, but it can provide a DWI defense against the results of the test.

The officer administering the test must:

  • Instruct and demonstrate to the suspect to place his or her left foot on the line and right foot heel-to-toe in front of it
  • Make sure the suspect understands this position must be held while the instructions are relayed
  • Stop the instructions until the suspect is back in position if he or she breaks from the pose
  • Tell the suspect not to begin until instructed
  • Demonstrate two or three heel-to-toe steps
  • Ask the suspect to take nine heel-to-toe steps down the line, turn around and take nine steps back
  • Have the suspect count his or her first step from the heel-to-toe position as the first step
  • If the suspect staggers, steps off the line, stops or stumbles, have him or her continue from the point of interruption

While performing the Walk and Turn Test, the suspect must keep both arms down, watch his or her feet, count the steps out loud and not to stop walking until the test is complete. If the suspect indicates that he or she doesn’t understand the instructions, the officer can repeat misunderstood parts but not the entire instructions.

When field sobriety tests may not have significant impact on a DWI case if the tests are used only as a tool to help an officer decide whether further action is required. Field sobriety tests can become a critical piece of evidence in a DWI case when a BAC or breath test was refused or the test has been found to be unreliable and suppressed. In those cases, the guidelines set for test administration may provide the support your DWI attorney needs to weaken or even exclude the field sobriety test results.

Some DWI courts may admit field sobriety tests that were administered imperfectly and let the DWI attorney argue the inaccuracy. Other DWI courts have ruled tests not administered according to the NHTSA training are inherently unreliable and excluded as evidence.

Tyson Mutrux
The Mutrux Law Firm
1717 Park Avenue, St. Louis, MO 63104
Phone: 314-270-2273|573-268-7316
Tyson@TysonMutrux.com

Below are three excellent videos about field sobriety tests.  The attorney in the video is not associated with Tyson Mutrux or the Mutrux Law Firm, but the content applies to Missouri and Illinois DWI Cases.

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