Standardized Field Sobriety Tests (“SFST’s”) are a set of assessments administered by police officers to individuals believed to be driving while under the influence of alcohol or drugs and are intended to detect signs of impairment referred to as “clues.”
SFST’s were developed as a result of research that was conducted in the 1970’s at the Southern California Research Institute, and was funded by the National Highway Traffic Safety Administration. The most common SFST’s utilized by law enforcement are the One-Leg Stand test, the Walk and Turn test, and the Horizontal Gaze Nystagmus test.
One Leg Stand Test
The One Leg Stand test is classified as a “divided attention” test, meaning that, under normal circumstances, it can be properly performed by most individuals. Because a person impaired by alcohol or drugs generally has difficulty dividing their attention between mental and physical tasks, they are unable to perform the test successfully.
In the one leg stand test, the subject is asked to stand with one foot approximately six inches off the ground and count thousands until instructed to put the foot back down. The test is timed for thirty seconds while the administrator looks for the following clues of impairment:
● Hopping jumping to keep balance
● Swaying while balancing
● Putting arms out to balance
● Putting the foot down on the ground
According to the NHTSA standards, if the subject exhibits two or more clues, he or she is presumed to have a blood alcohol content of 0.08 or greater. The results of the one leg stand test can be negatively affected if it is administered at night, without an actual line for the subject to walk on, or if there is a pre-existing medical condition, or on an irregular surface, among other reasons.
Walk and Turn Test
The Walk and Turn Test is also a divided attention test. During the walk and turn test, the subject is asked to take nine steps along a straight line, turn on one foot, and take nine steps back to the starting point. There are eight potential clues of impairment for the walk and turn test:
● Poor balance during the instruction phase
● Starting the test before instructed to
● Stopping while walking to maintain or regain balance
● Failing to touch feet heel-to-toe on each step
● Stepping off the line while walking
● Putting out arms to maintain or regain balance
● Turning improperly
● Taking an incorrect number of steps
According to the NHTSA standards, if the subject exhibits two or more clues, he or she is presumed to have a blood alcohol content of 0.08 or greater. The walk and turn test can be negatively affected by the surface it is conducted on and by some physical conditions that, for example, affect balance, among other things.
Horizontal Gaze Nystagmus Test
Horizontal Gaze Nystagmus test is the involuntary jerking of the eye occurring naturally as it moves to the side. Nystagmus usually occurs when the eye rotates at high peripheral angles. Alcohol or drug impairment can amplify nystagmus and cause it to happen at lesser angles. Alcohol or drug impairment can also impair the eye’s ability to smoothly track a moving object.
During the horizontal gaze nystagmus test, the subject’s eyes are observed to see if they are able to follow a slowly moving object, such as a finger or pen, horizontally without nystagmus occurring. Each eye can exhibit up to three clues for a total of six:
● The eye is not able to follow the object smoothly
● The eye jerks at the maximum deviation, the farthest point it can move to the side
● The angle at which eye jerking begins is within 45 degrees of center
According to the NHTSA standards, if the subject exhibits four or more clues, he or she is presumed to have a blood alcohol content of 0.08 or greater. The horizontal gaze nystagmus test is often criticized for failing to account for certain health conditions, such as glaucoma, that negatively affect the ability to successfully perform the test. Further, various chemicals, such as caffeine and nicotine, can potentially cause nystagmus in the absence of alcohol or drugs.
The criminal defense attorneys of Brassel Alexander, LLC have extensive experience defending individuals charged with driving while under the influence of alcohol or drugs. If you or someone you know has been charged with DUI or DWI in Maryland, contact our attorneys today.