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McLean Field Sobriety Tests

Standard field sobriety tests (SFSTs) are tests designed to be administered during a traffic stop to aid an officer in determining if a driver is intoxicated or otherwise impaired. There are only three McLean field sobriety tests and they are the Horizontal Gaze Nystagmus (HGN) test, the Walk-and-Turn test, and the One-leg Stand test.

Contact an experienced DUI lawyer for more information about field sobriety tests and your rights during a DUI stop.

Horizontal Gaze Nystagmus Test

The Horizontal Gaze Nystagmus test is a test during which officers observe a driver’s eyes for involuntary jerking that occurs as the person looks from side-to-side. When administered accurately, this is supposedly the most accurate of the field sobriety tests in McLean. Before administering this test, officers are trained to check the driver’s eyes for equal pupil size, resting nystagmus, and equal tracking – whether both eyes follow a stimulus together. Officers are also trained to ask if the individual suffers any health conditions that impact their eyes and if they wear glasses or contacts as this may impact the validity of the test. When administering this test, officers hold a stimulus – typically a pen or the tip of the officer’s finger 12-15 inches away from the person’s nose and slightly above eye-level. The officer will then move this stimulus from side-to-side and watch the person’s eyes for nystagmus at maximum deviation, the onset of nystagmus prior to 45 degrees, and a lack of smooth pursuit.

Walk and Turn Test

The Walk-and-Turn test is a divided attention field sobriety test. The individual taking the test will be instructed to:

  • Place one foot in front of the other heel-to-toe on an imaginary or real line
  • Place the person’s arms by their side
  • Maintain this position until instructed to start 
  • The person will then be instructed to take nine heel-to-toe steps out
  • Turn around by leaving one foot planted and taking a series of small steps
  • Take nine heel-to-toe steps back on the line

The officer will be looking to see if the individual starts the test too soon, stops before concluding the test, does not touch heel-to-toe, steps off the line; uses their arms to balance, makes an improper turn, and/or takes an incorrect number of steps.

One Leg Stand Test

The One Leg Stand test is another divided attention field sobriety test. For this test, the officer will instruct the individual to:

  • Stand straight with their feet together
  • Keep their arms by their side and maintain this position until told to begin the test
  • The person would further be instructed to raise either foot
  • Keep that foot raised approximately six inches from the ground and hold it parallel to the ground
  • Keep both legs straight while maintaining their arms at their side
  • Keep their eyes on the raised foot, and to count aloud “one thousand one, one thousand two,” et cetera until instructed to stop

The officer will observe the person for what should be no longer than 30 seconds to see if they sway while balancing, uses their arms for balance, hops, and/or puts their foot down.

Do Field Sobriety Tests Need to Administered in a Certain Way?

These standardized tests must be administered in a standardized manner prescribed by the National Highway Traffic Safety Administration (NHTSA) in order to obtain validated identifications of impairment. In addition, officers must use standardized clues to assess the person’s performance and use standardized criteria when interpreting their performance for these tests to be valid.

The Weight of Field Sobriety Tests at a DUI Trial

Standard field sobriety tests carry significant weight in a DUI trial in McLean. When administered appropriately, there are scientific studies that back up the credibility of these tests when it comes to determining if a person is impaired. Officers use field sobriety tests in the majority of DUI stops and courts are familiar with how these tests should be administered.  Judges also have experience with seeing videos of a person’s performance on these tests and subsequently learning the person’s blood alcohol concentration and associate the two. For example, a judge will likely believe that a person has a significantly high BAC if the person is recorded stumbling severely and unable to successfully complete field sobriety tests. An accomplished lawyer will have experience challenging these test results and their validity in a DUI case.

Refusing Field Sobriety Tests in McLean

McLean field sobriety tests are voluntary. A person cannot legally be compelled to complete field sobriety tests. Therefore, a person can always refuse to perform field sobriety tests. If there is a chance that a person is impaired, the completion of a field sobriety test may not be advisable as their performance can be used against the person in court. While the mere refusal to perform a field sobriety test is not itself an admission of guilt, this refusal can be taken into consideration by the court as to whether there was probable cause to arrest the person.

A person can still be arrested under suspicion of a DUI if they refuses to perform field sobriety tests. 

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