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Standard Field Sobriety Tests in Mississippi

The National Highway Traffic Safety Administration (NHTSA) has recommended three standardized field tests that can be administered to establish probable cause for DUI.  All field tests are voluntary; there are no penalties for not submitting to any field test.

(1)    Horizontal Gaze Nystagmus (HGN):  The HGN test is often the first test administered.  First, the officer instructs the driver to stand with his heels together and hands at his sides.   If the driver is wearing glasses, they should be removed.  Then the officer tells the driver to follow an object, such as a pen, with his eyes and continue to do so until told to stop.   The officer hold the object 12-15 inches from the driver’s nose, at a point slightly above eye level, and checks to ascertain that the driver’s pupils are the same size.  Different size pupils may indicate a head injury, so if the pupils are not the same size, the test should not be performed.  If the eyes jerk while just staring straight ahead, this may indicate a medical condition and the results of the test may not be valid.  Next the officer moves the object from side to side and checks to make sure the eyes track the object at the same speed.  If there is unequal tracking, there is a high probability that the driver has a medical condition that would invalidate the test.  If there is no sign of a medical condition, the officer checks for the 6 signs of alcohol impairment: (1) involuntary nystagmus (jerking eye movements) as the eyes follow the pen from side to side, (2)   distinct and sustained nystagmus at maximum deviation (when the eyes are jerking when the pen is moved as far to one side as the eyes can follow and held there), and (3) onset nystagmus prior to 45 degrees (when the eyes jerk before the object reaches a 45 degree angle to the driver).  The officer observes each eye separately for a total of 6 signs.   According to the NHTSA, if a driver exhibits four or more signs, it is likely that his BAC is above .1%

The HGN test can be used to show probable cause for making a DUI arrest, however, it cannot be used as evidence of DUI.   A driver could fail a HGN test if the officer administered it incorrectly or if the driver has a medical problem or physical abnormality that he might not even be aware of.   For these reasons and because there are no penalties for refusing to take the test, a driver should decline to take it.

(2)    The Walk and Turn Test (WAT):  The WAT test is often the second test administered.  In this test the officer is trained to first find a reasonably flat surface that is free of gravel or other debris.  The officer then asks the driver if he has condition that would prevent him from performing the test.   If the driver is wearing shoes with heels that are higher than two inches the officer must allow the driver to take off the shoes before the test.  The officer then indicates a straight line, or if there is not one on the road he tells the driver to imagine a line.   The officer instructs the driver to place his left foot on the line and place his right foot in front of it so his feet are touching heel to toe and place his arms at his sides.  The officer also must demonstrate this starting position.  When the driver is in position, the officer tells him to stay in position until he is told to begin and the officer asks the driver if he understands the instructions.  The officer then tells the driver that when told to begin, he should take 9 heel-to-toe steps forward, turn, and take 9 heel-to-toe steps back; the officer should demonstrate 3 steps.  The officer then tells the driver that when he turns, he should keep his front foot on the line and turn by taking small steps with his other foot; the officer should demonstrate the turn.  The officer will instruct the driver to keep his hands at his sides, watch his feet, count out loud, and once he has begun he should finish the test without stopping.  The officer should again ask the driver if he understands and then tell him to begin.  From when the driver is placed into starting position, the officer checks for 8 signs: (1) the driver cannot balance during the instructions, (2) the driver starts the test before being told to do so, (3) the driver stops while walking, (4) the driver misses heel-to-toe, (5) the driver steps off the line, (6) the driver uses his arms to balance, (7) the driver either turns incorrectly or loses his balance while turning, and (8) the driver takes the wrong number of steps.  If the driver exhibits 2 or more signs, he likely has a BAC that is above .1%.   However, it is important to note that only the above enumerated signs are indicators of a high BAC.  Other actions, such as swaying without losing balance, using the arms to balance during the instruction phase, or counting incorrectly, are not to be counted in the WAT test.

There is the risk that the WAT test will be administered incorrectly, additionally, some people will exhibit 2 or more of the 6 signs even when sober.   For these reasons, and because there is no penalty for refusing to take the test, a driver should  decline to take it.

(3)    The One Leg Stand (OLS) The OLS test is often the third test administered.  In this test the police officer first demonstrates standing on one foot, and then instructs the driver to stand on one foot while the officer times him for 30 seconds.  There are 4 signs the officer checks for:  (1) the driver puts his foot down, (2) the driver raises his arms for balance, (3) the driver sways, and (4) the driver hops.  If the driver exhibits 2 or more signs, he likely has a BAC of .1% or higher.   The NHTSA has ranked the OLS as a more accurate test than the WAT, so if a driver fails the WAT but passes the OLS, this can be used to challenge the results of the WAT.

There are risks to the OLS test because some people will fail this test even when sober and determining what qualifies as swaying is subjective.  Therefore, like with all field sobriety tests, there is no penalty for refusing to take the OLS, so a driver should decline to take it.


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