The Walk and Turn and One Leg Stand
The Walk and Turn and One Leg Stand are the second and third evaluations that officers use on the roadside and both are classified as a divided attention test. NHTSA has determined that divided attention tests are a good measure of driving ability because when operating a motor vehicle, you are required to pay attention to many things. For example, if you were driving down I85, you have to pay attention to your speed, the cars in front of you, the cars behind you, the cars beside you, the speed of traffic, what’s on the radio, who you may be talking to in the car with you, etc…you get the point! Your attention is divided between many different things.
Both of these evaluations are designed to simulate this attention division. For instance, in the walk and turn evaluation, a subject is instructed in the following manner:
- Imagine a line from where you are standing to (a designated point).
- Place your left foot on that line and place your right foot in front of your left foot with your heel touching your toe.
- Remain in that position until I tell you to begin.
- When I tell you to begin, I want you to take 9 heel-to-toe steps down that imaginary line (officer demonstrates), when you reach the 9th step, leave your left foot on that line, take a series of small steps around your left foot back to the line and take 9 heel-to-toe steps back (officer demonstrates).
- When you begin walking, don’t stop walking until you are finished, keep your hands to your side, look at your feet while walking and count your steps out loud.
- You may begin when you are ready
As you can tell, there is a lot to think about during this entire evaluation. Failure to do things as you are instructed results in a “clue.” For the Walk and Turn evaluation there are 8 possible clues and for the One Leg Stand, there are 4. The more clues shown by a subject, the better an officer can discern impairment. When explained and demonstrated accurately, NHTSA has found that the Walk and Turn and One Leg Stand evaluations are 68% and 65% accurate, respectively.
Unlike the HGN evaluation, these are not scientific. They can be impacted by a multitude of things. A person’s balance and vestibular issues, environmental conditions (extreme wind or cold), weight, or age can have an impact on how they perform the evaluations. Officers are trained to take those things into consideration when making decisions out on the side of the road; however, it is rare that they are identified and not attributed to impairment.