The Standardized Field Sobriety Testing (SFST) battery consists of three tests: (1) Horizontal Gaze Nystagmus (HGN), (2) Walk and Turn (WAT), and (3) One Leg Stand (OLS). These tests help the officer to determine impairment and establish probable cause for arrest.
HORIZONTAL GAZE NYSTAGMUS (HGN)
Horizontal Gaze Nystagmus (HGN) is an involuntary jerking of the eye, which is exaggerated when a person is under the influence of alcohol. During the HGN test, the officer will observe the eyes of a suspect as they follow a stimulus (such as a pen or small flashlight) held 12 to 15 inches in front of them. As the stimulus is moved horizontally, the officer looks for three indicators of impairment in each eye. The officer looks to see if (1) the eye cannot follow a moving object smoothly, (2) if jerking is distinct when the eye is at maximum deviation, and (3) if the angle of onset for the jerking is within 45 degrees of center. There are a total of 6 clues the officer is looking for, 3 in each eye. If the officer detects 4 or more clues, research suggests that there is an 88% chance that the suspect has a BAC of at least 0.08.
WALK AND TURN (WAT)
The Walk and Turn (WAT) test is a divided attention test, which requires a suspect to listen and follow instructions while performing a physical act. People who are impaired have difficulty performing tasks that require dividing their attention between simple mental and physical exercises. The WAT requires a suspect to take 9 steps, heel-to-toe, along a straight line. After taking the steps, the suspect must turn around on one foot and take 9 steps back, heel-to-toe, along the same straight line. The WAT has a total of 8 clues the officer is looking for: (1) Can't keep balance while listening to instructions, (2) Starts too soon, (3) Stops walking to steady self / regain balance, (4) Misses heel-to-toe, (5) Steps off the line, (6) Use arms for balance or raises arms over 6 inches, (7) Improper turn (loses balance, stumbles, or turns in a way other than officer demonstrated), and (8) Incorrect number of steps performed. Research suggests that when a suspect demonstrates 2 or more of the 8 clues, there is a 79% probability that the suspect will have a BAC of at least 0.08.
ONE LEG STAND (OLS)
The One Leg Stand (OLS) is another divided attention test. The OLS requires the suspect to stand with one foot approximately 6 inches off the ground while counting out loud by thousands. The suspect will not be told how long the test lasts and will be required to continue until requested to put his foot down. The officer will time the suspect for a period of 30 seconds. In the OLS, the officer will look for the following 4 clues of impairment: (1) Sways while balancing, (2) Uses arms to balance or raises arms over 6 inches, (3) Hopping, and (4) Putting their foot down before the 30 second period elapses. If the suspect puts their foot down 3 times, they are unable to perform the test. NHTSA research suggests 83% of suspects who display 2 or more clues have a BAC of at least 0.08.
Contact Adkins Law to schedule a free DWI consultation with an DWI lawyer, DUI lawyer, DWI attorney, DUI attorney. Adkins Law is located in Huntersville, North Carolina and primarily serves Huntersville, Cornelius, Davidson, Charlotte, Mecklenburg County, Iredell County, Gaston County, and Cabarrus County.