DWI Field Sobriety Tests

Fairfax DWI Field Sobriety Tests

The vast majority of Fairfax DWI arrests begin when an officer pulls a vehicle over for some perceived traffic violation. After noticing an odor of alcohol, the law enforcement official will ask the driver to perform a series of field sobriety tests. It is essential that the officer ask and not order a suspect to perform these tests, as it could have serious impacts upon one’s case should an arrest be made.

Approved with strict guidelines provided by the National Highway Traffic Safety Administration (NHTSA), there are a variety of field sobriety tests that law enforcement officers typically ask a suspect to perform including: the Horizontal Gaze Nystagmus (HGN), the walk-and-turn test, and the one-legged stand.

Horizontal Gaze Nystagmus (HGN)

Officers administer the Horizontal Gaze Nystagmus test by asking suspect to follow a pen or flashlight with their eyes only. The police will then watch to see whether the individual’s following of the waving object is smooth or jerky to determine if they are intoxicated or not. This test isn’t particularly relevant to Fairfax DWI cases however, as the vast majority of judges require an expert to testify to the test’s usefulness and it is rare that any experts actually show up in court.

Walk-and-Turn Sobriety Test

In administering the walk-and-turn test, the officer instructs the defendant to stand with one foot in front of the other, touching heel to toe. Suspects are then asked to hold this position while being directed as to their next steps. Finally, the officer requests that the individual takes nine steps in a straight line and then pivot at the end. (The line may be real or imaginary.)

Commonly, law enforcement officials are watching to see if the suspect exhibits any of the seven indicators:

  1. Inability to maintain start position
  2. Starting too early
  3. Needing to stop to regain balance
  4. The existence of gaps between feet while taking steps (if the heel actually makes contact with the toe on each step)
  5. Loss of balance on the turn
  6. Use of arms to maintain balance
  7. Inaccurate number of steps taken

NHTSA research indicates that if two or more indicators are present, then the chance the driver has a BAC of .08 or higher is 79%, prompting most officers to place the individual under arrest for a Fairfax DWI offense.

One-Legged Stand Sobriety Test

To conduct the one-legged stand test, the officer asks the driver to stand on one leg with the other foot six inches off the ground. The driver is then instructed to count out loud by thousands (one one-thousand, two one-thousand, etc.) while the law enforcement official looks for four indicators:

  1. Starting too early
  2. Inability to maintain balance and putting foot down
  3. Use of arms to maintain balance
  4. Inability to count accurately

NHTSA research shows a DWI suspect who shows two or more indicators will have a BAC of.08 or higher 83% of the time, generally giving police enough reason to place the motorist under arrest.

Other Fairfax Field Sobriety Tests

Law enforcement officials may administer several other tests as well, even though they are not approved by NHTSA. Often times, these include asking the suspect to recite the alphabet and count backwards. Officers may also request that suspects try to touch their nose with their fingers or to count on their hands. Police may also administer a preliminary breath test to determine whether the individual should be arrested and charged with a Fairfax DWI.

Field sobriety tests are important in all drunk driving-related cases as they are often the deciding factor in whether it was legal for the officer to make the arrest or not. These examinations are even more critical in cases where no blood or breath test was taken as the suspect’s performance will be the only evidence of intoxication that Prosecutor’s can present against defendants in court.

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