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DWI Stops and the Use of Standardized Field Sobriety Tests

Standardized Field Sobriety Tests (“SFSTs”) are used in North Carolina to help determine whether a suspected driver is actually impaired. SFSTs, along with other preliminary factors, will be used to determine whether probable cause for impairment exists. Upon determination of probable cause for impairment, the officer should issue a preliminary breath test to determine whether impairment is the result of alcohol or another impairing substance. SFSTs are claimed to have been scientifically validated and thus good indicators of impairment. However, to actually be scientifically validated, SFSTs must be properly administered as variation will likely produce unscientific results.

Many people mistakenly believe SFSTs consist of tests such as saying the alphabet backwards, touching your finger to your nose, etc.. In reality, only 3 tests have been “scientifically” approved for use as SFSTs – Horizontal Gaze Nystagmus, Walk and Turn, and the One Legged Stand. These are known as psychophysical tests and are meant to divide the suspect’s attention.

The hardest to properly conduct and yet the test most often used is Horizontal Gaze Nystagmus (“HGN”). Nystagmus is an involuntary jerking of the eyes and there are numerous causes including alcohol, drugs, medications, medical conditions, stress, physiological conditions, and more. HGN is an involuntary jerking as the eyes move from side to side of which the person is often unaware. Proper administration of HGN consists of 3 phases each requiring the officer use a stimulus which the suspect must follow with his or her eyes. The test should begin with the left eye and the stimulus placed 12-15 inches from the nose at all times. The first phase tests for smooth pursuit as the eyes follow the stimulus from center to maximum deviation and then back; the officer should be moving the stimulus from center to maximum deviation at a pace of about 2 seconds. (Maximum deviation occurs at the furthest point of peripheral vision.) The second phase tests for nystagmus at maximum deviation and requires the officer hold the stimulus at maximum deviation for a minimum of 4 seconds for each eye. The third phase tests for the onset of nystagmus prior to 45 degrees. The officer should move the stimulus at a pace of about 4 seconds from center to 45 degrees. Prior to conducting any part of the HGN testing, the officer should ensure the suspect is not wearing glasses, the suspect has equal pupil size, the suspect does not have resting nystagmus, and that there are no lights flashing or shining directly in the suspect’s line of vision.

The second SFST an officer should conduct is the Walk and Turn (“WAT”) test. WAT involves an individual taking 9 heel-to-toe steps in a straight line, turning, and taking 9 heel-to-toe steps to return to the original location. During this test, the officer will be observing the individual for 8 indicators of impairment – 1) the individual cannot keep balance during the instructional phase, 2) the individual begins walking before instructions are complete, 3) the individual pauses for several seconds while walking the line, 4) the individual leaves more than half an inch between their heels and toes while walking, 5) the individual steps at least one foot entirely off the line, 6) the individual raises one or both arms more than 6 inches from their sides to balance, 7) the individual fails to follow instruction when turning around, and 8) the individual takes more or less than 9 steps in each direction. Prior to the test, officers must instruct the individual on how to conduct this test and will instruct the individual to count their steps aloud while looking at their feet, although failure to count aloud is not one of the 8 indicators of impairment.

The third and final SFST an officer should conduct is the One Legged Stand (“OLS”) test. OLS requires the individual to balance on one leg for approximately 30 seconds and therefore should not be conducted on individuals over 65 years old or more than 50 pounds overweight. During OLS the individual will be asked to stand on one leg and hold the other leg out with the foot approximately six inches off the ground, parallel to the ground. The arms must be kept at the sides while watching the raised foot and counting aloud in the manner of one thousand and one, one thousand and two, etc. During the performance of OLS, officers will be looking for 4 indicators of impairment – 1) whether the suspect sways (side-to-side or back-and-forth) during the test, 2) whether the individual moves their arms six or more inches from their sides to maintain balance, 3) whether the individual hops in order to maintain balance, and 4) whether the individual touches his foot to the ground to help maintain balance.

Proper instruction and application of SFSTs by an officer is critical to the validity of SFSTs as a “scientific” tool in forming probable cause for impairment. Depending on the circumstances of your case, improper application of SFSTs may result in a lack of probable cause and therefore a dismissal of your charge. A qualified attorney will be better able to assist you as you prepare to defend a DWI charge. The Clifford Division of Clifford Clendenin & O’Hale, LLP has taken classes on DWI defense, the proper administration of SFSTs and has successfully handled numerous DWI cases. If you need a qualified DWI attorney who will fight for your rights and attempt to obtain the best possible outcome for your case, contact the Clifford Division at 336-574-2788.

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