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Standardized Field Sobriety Tests

What are standardized field sobriety tests? If an individual is stopped and suspected of drunk driving, it is typical that the police officer will ask the subject to perform standardized field sobriety tests (SFTS). The three most common tests performed by a driver at the road side are:

  1. The horizontal gaze nystagmus;
  2. The walk-and-turn test; and
  3. The one leg stand test.

Police officers are trained to observe the performance by the suspect of these tests and to note any possible clues. Clues are mistakes made by the subject during the tests. Clues may help the officer to determine if the driver is impaired. Also, if the officer believes the individual is impaired or under the influence it can allow the officer to establish establish probable cause for a drunk driving arrest.

field sobriety tests

Horizontal Gaze Nystagmus (HGN) Clues

The horizontal gaze nystagmus, also known as the “HGN”, is typically the first test performed by a an officer. There are a maximum of 6 clues during the HGN, three clues per eye. Nystagmus refers to the involuntary jerking of the eyes. Horizontal  is the direction in which the officer will typically test a suspect. Officers will often perform the VGN, which stands for vertical gaze nystagmus. The VGN is to detect the presence of drugs or CDS in the driver’s system.

Involuntary jerking of the eyes may be noticeable when a person is impaired. Studies have found that if a person’s blood alcohol concentration increases, that person’s eyes will begin to jerk as they move side-to-side.  During the HGN, the police officer will have the driver follow a small item like a pen or the tip of the officer’s finger with their eyes only . The six clues during the horizontal gaze nystagmus are:

  1. the person’s eyes begins to jerk prior to a 45 degree angle
  2. as the eye moves from side to side it will jerk
  3. when an eye moves as far to the side as possible and is held constant at that location it will jerk.

As these three clues are checked for both eyes there are a maximum total of 6 clues for the HGN.

Walk And Turn Test Clues

The walking turn test has two phases, 1) the instructional phase and 2) the walking phase. Police officer will ask an individual to stand heel-to-toe while giving the instructions for the test. The driver must keep his arms to the side and listen to the instructions without starting the test early or before the officer has completed his instructions.

The officer will instruct the driver to take 9 heel to toe steps down along an imaginary line, turn using small baby steps and take 9 heel to toe steps back to the original position. The officer will instruct the driver to count the steps out loud and watch their feet during the test. During the turn, the subject is to keep their front foot on the line, and turn in the manner is instructed by the officer. Taking small baby steps around the front foot. The clues the officer is looking for during a walk and turn test are:

  1. The subject cannot keep their balance while listening to the instruction
  2. Driver starts the test too soon
  3. The subject stops the test while walking one of the set of 9 steps enter subject does not touch Heel To Toe on any of the nine steps down or back
  4. The individual steps off the imaginary line during the walking phase of the test
  5. The person uses their arms to balance before ordering the test
  6. The individual makes an improper turn that is not what the police officer instructed and enter the person takes an incorrect number of steps either the first nine or the second nine.

One-Leg Stand Test Clues

The final test that is given on the roadside during the DUI want investigation is called the one-leg stand test. This test is intended to detect close up truck driving through the balancing portion of the test as well as processing the information. There are two stages or phases of the test, 1) the instructional phase and 2) the balancing and counting phase. There are a total of 4 clues an officer can note during the one leg stand test. Those four clues include enter

  1. swaying while balancing
  2. the driver uses his or her arms to balance during the test
  3. hopping during the test and
  4. the subject puts his or her foot down during the test.

The officer will instruct an individual to raise either their right or left foot approximately 6 inches off the ground and and keep both legs straight during the test. In addition, the officer will instruct subject to maintain their raised foot parallel to the ground. The officer will tell the driver to look at the foot that he or she raises and count out loud, “one-thousand one, one thousand two” and so on until the individual reaches “one thousand thirty.”

During that 30 second count the officer is looking for the previously mentioned four clues. The standardized field sobriety tests or meant to establish probable cause and are not an indication that a driver is drunk or impaired. However the performance on the standardized field sobriety tests will often be used in court by the state to prove a drunk driving charge.

Drunk Driving Defense Lawyer in Maryland 

Attorney Randolph Rice is a Maryland DUI and DWI defense lawyer. Prior to representing individual charged with drunk driving, he was a prosecutor with the Baltimore County State’s Attorney’s office. During his career as both a prosecutor and a private DUI defense lawyer, he has represented hundreds of individuals charged with DUI & DWI in Maryland. If you are facing drunk driving charges in Maryland, contact his office today to schedule a free consultation that discuss your field sobriety tests.