This test requires that a suspect take nine steps along a line, walking heel to toe while counting each step out loud. At the ninth step the individual must pivot, taking several small steps while keeping one foot on the line and return in the same heel to toe fashion still counting aloud. This test is designed to evaluate a person’s balance, small muscle control, and short term memory. It’s important to keep in mind that the officer, prior to observing the suspect in the performance stage must give a demonstration during the instruction phase. In addition, if there isn’t a visible line on the ground the officer must use something to simulate a line to ensure the tests validity.
During the walk and turn test the officer will look for the following eight performance clues:
1. the inability to balance during instruction,
2. beginning the test too soon,
3. stopping while walking to steady oneself,
4. touching heal to toe while walking,
5. walking off of the line,
6. use of arms to balance,
7. loss of balance during the pivot or improper picot, and
8. taking incorrect number of steps.
Generally people over the age of 60, overweight by more than 50 pounds, or who have some type of physical injury history (prior accident) or an inner ear disorder may have difficulty performing this test even if they are sober. While there is no exact failing grade on this test, according to the NHTSA 79% of all subjects who show two or more of the above eight clues are thought to have a BAC of .08 or greater. This is obviously a subjective determination which a good defense attorney should attack.