One Leg Stand

9.5.5 One Leg Stand

9.5.5.1 Procedures for One-Leg Stand Testing[1]

“1. Instructions Stage: Initial Positioning and Verbal Instructions

Initiate the test by giving the following verbal instructions, accompanied by demonstrations.

"Please stand with your feet together and your arms down at the sides, like this." (Demonstrate)

"Do not start to perform the test until I tell you to do so."

"Do you understand the instructions so far?" (Make sure suspect indicates understanding.)

2. Demonstrations and Instructions for the Balance and Counting Stage

Explain the test requirements, using the following verbal instructions,  accompanied by demonstrations:

"When I tell you to start, raise one leg, either leg, with the foot approximately six inches off the ground, keeping your raised foot parallel to the ground.” (Demonstrate one leg stance.)

"You must keep both legs straight, arms at your side.”

"While holding that position, count out loud in the following manner: “one thousand and one, one thousand and two, one thousand and three, until told to stop.” (Demonstrate a count, as follows: "one thousand and one, one thousand and two, one thousand and three, etc." Officer should not look at his foot when conducting the demonstration - OFFICER SAFETY.)

"Keep your arms at your sides at all times and keep watching the raised foot."

"Do you understand?" (Make sure suspect indicates understanding.)

"Go ahead and perform the test." (Officer should always time the 30 seconds. Test should be discontinued after 30 seconds.)

Observe the suspect from a safe distance. If the suspect puts the foot down, give  instructions to pick the foot up again and continue counting from the point at  which the foot touched the ground. If the suspect counts very slowly, terminate the test after 30 seconds.”

9.5.5.2  Test Interpretation[2]

“You may observe a number of different behaviors when a suspect performs this test. The original research found the behaviors listed below are the most likely to be observed in someone with a BAC above 0.10. Look for the following clues each time the One-Leg Stand test is administered.

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

B. Uses arms for balance. Suspect moves arms 6 or more inches from the side of the body in order to keep balance.

C. Hopping. Suspect is able to keep one foot off the ground, but resorts to hopping in order to maintain balance.

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

Note: If suspect can't do the test, record observed clues and document the reason for not completing the test, e.g. suspect’s safety.

Remember that time is critical in this test. The original research has shown a person with a BAC above 0.10 can maintain balance for up to 25 seconds, but seldom as long as 30.

9.5.5.3 Scoring

Based on original research, if an individual shows two or more clues or fails to complete the One-Leg Stand, there is a good chance the BAC is above 0.10”[3]. (So, two clues out of four would classify the driver as a failure).

“Using that criterion, you will accurately classify 65% of the people you test as to whether their BAC's are above 0.10.

Observe the suspect from a safe distance and remain as motionless as possible during the test so as not to interfere. If the suspect puts the foot down, give instructions to pick the foot up again and continue counting from the point at which the foot touched the ground. If the suspect counts very slowly, terminate the test after 30 seconds”[4].

9.5.5.4  Test Conditions[5]

“One-Leg Stand requires a reasonably dry, hard, level, and non-slippery surface. Suspect's safety should be considered at all times.”

“The original research indicated that certain individuals over 65 years of age, back, leg or inner ear problems, or people who are overweight by 50 or more pounds had difficulty performing this test. Individuals wearing heels more than 2 inches high should be given the opportunity to remove their shoes.”

[1]Id at VIII-12

[2]Id at VIII-13

[3]Id.

[4]Id.

[5]Id. at VIII-13