If you are ever stopped by a law enforcement officer and the officer believes you are driving under the influence, or DUI, you will likely be asked to perform a series of field sobriety tests. Unless you have been through these tests before they may seem confusing, even if you haven’t been drinking. Moreover, it may appear as those the officer subjectively decides whether or not you passed the tests. The reality is that it is entirely up to the officer to decide whether or not you passed. If you are performing the three standardized field sobriety tests, or FSTs, there are specific indicators that an officer is supposed to use to determine whether a subject passes or fails. Knowing how the tests work ahead of time and what an officer looks for when evaluating your performance could make the difference between passing and failing someday.
Although a law enforcement officer can use just about any FST he/she wishes, most use the three standardized tests. “Standardized” simply means they have been approved by the National Highway Transportation Safety Administration, or NHTSA. The three standardized tests as well as the criteria used to evaluate passage are as follows:
- Horizontal Gaze Nystagmus (HGN) – in this tests the examiner will typically hold a penlight in front of your eyes and ask you to follow the light without moving your head.
“The examiner looks for three indicators of impairment in each eye: if the eye cannot follow a moving object smoothly, if jerking is distinct when the eye is at maximum deviation, and if the angle of onset of jerking is within 45 degrees of center. If, between the two eyes, four or more clues appear, the suspect likely has a BAC of 0.08 or greater.”
- Walk and Turn – you will need to take nine steps in a straight line walking heel to toe. You must then execute a turn on one foot and return walking the same way (heel to toe).
“The examiner looks for eight indicators of impairment: if the suspect cannot keep balance while listening to the instructions, begins before the instructions are finished, stops while walking to regain balance, does not touch heel-to-toe, steps off the line, uses arms to balance, makes an improper turn, or takes an incorrect number of steps. NHTSA research indicates that 79 percent of individuals who exhibit two or more indicators in the performance of the test will have a BAC of 0.08 or greater.”
- One Leg Stand – you must stand with one leg about six inches off the ground and count slowly. The examiner will count to 30 before you may put your foot down. You cannot use your arms for balance.
“The officer looks for four indicators of impairment, including swaying while balancing, using arms to balance, hopping to maintain balance, and putting the foot down. NHTSA research indicates that 83 percent of individuals who exhibit two or more such indicators in the performance of the test will have a BAC of 0.08 of greater.”