DUI Investigations & The One Leg Stand Test

Below is the instruction given by the National Highway Transportation Safety Administration (NHTSA) to DUI law enforcement officers on how to administer and score the "One Leg Stand" Field Sobriety Test:

Provide the DUI suspect the exact instructions listed below:

STAND WITH YOUR HEELS TOGETHER AND YOUR ARM DOWN AT YOUR SIDES LIKE THIS (Demonstrate how you want the suspect to stand).

WHEN I TELL YOU, RAISE ONE LEG ABOUT SIX INCHES OFF THE GROUND AND HOLD THAT POSITION. AT THE SAME TIME COUNT RAPIDLY FROM 1001 TO 1030, while watching your foot. Like this.

DO YOU UNDERSTAND? (Do not continue until the suspect indicates that he understands.) BEGIN BY RAISING EITHER YOUR RIGHT OR YOUR LEFT FOOT.

(At the end of the count or after about 30 seconds, if the count is slow, tell the person to put his foot down-if necessary).

How to Score The One Leg Stand Field Sobriety Test

Research has found that the behaviors listed below are most likely to be observed in someone with a BAC of 0.10 percent or higher. In scoring this test, give only one point for each item observed, even if it is observed more than once. The maximum possible score on this test is five points.

1. The suspect sways while balancing. This refers to a side-to-side or back-and-forth motion while the suspect maintains the one leg-stand position.

2. Use arms for balance. He moves his arms six or more inches from the side of his body in order to keep this balance.

3. Hopping. He is able to keep one foot off the ground, but resorts to hopping on the anchor foot in order to maintain balance.

4. Puts foot down. The suspect is not able to maintain the on-leg-stand position, putting his foot down one or more times during the 30-second count.

5. Cannot do test. Score this item if the suspect puts his foot down three or more times during the 30-second count or otherwise demonstrates that he cannot do the test. If you score this item, give the suspect five points-the maximum for this test.

Remember that time is critical in this test. Research has shown that a person with a BAC of 0.10 percent can maintain his balance for up to 25 seconds, but seldom as long as 30.

If the person stopped for DUI scores two or more points on the One-Leg-Stand, there is a good chance his BAC is 0.10 percent or higher. So your decision point on this test is two. Using that standard, you will correctly classify about 65 percent of the people you test as to whether they are sober or drunk driving.

Test Conditions for The One Leg Stand

As with the Walk-and-Turn Test, the One-Leg-Stand should be given on level ground, on a hard, dry, non-slippery surface, and under conditions in which the DUI suspect will be in no danger should she fall. If these guidelines cannot be followed at the place where you stop the driver, you may be able to move to a better location. If not, base your decision on the Gaze Nystagmus Test alone.

Certain individuals are likely to have trouble with this test even when sober. People over 60 years of age often have very poor balance. (Since very few elderly people are stopped at roadside, specific guidelines have not been established for them on this test). This also applies to people who are more than 50 or more pounds overweight and to those with physical impairments that interferes with balance.

In administering this field sobriety test, make certain the DUI suspect's eyes are open and that adequate lighting exists. If you can see the suspect fairly well, then the light is adequate. Otherwise, use a flashlight to illuminate the ground. In total darkness, the one leg-stand is difficult even for a sober person.

Observe the suspect from about three feet away and remain relatively motionless while he is performing the test. Being too close just as in the Walk-and-Turn-Test_ makes the test more difficult. And, again, individuals with heels over two inches high should be given the opportunity to remove their shoes.

If the suspect puts his foot down, instruct him to continue to count from the point at which the foot touched the ground. And if the person counts very slowly, stop the test after 30 seconds have elapsed.

Scoring Sheet for the One-Leg-Stand Test

• Sways while balancing.
• Uses arms to balance.
• Hopping.
• Puts foot down.
• Cannot do test (puts foot down three or more times).
  (Decision: Point: 2 Clues)