Massachusetts DWI DUI OUI Field Sobriety Test Police Training Manual

In the Instructions Stage, the subject must stand with feet together, keep arms at sides, and listen to instructions. This divides the subject’s attention between a balancing task (maintaining a stance) and an information processing task (listening to and remembering instructions.)

In the Balance and Counting Stage, the subject must raise one leg, either leg, approximately six inches off the ground, toes pointed out, keeping both legs straight. While looking at the elevated foot, count out loud in the following manner: “one thousand and one,” “one thousand and two,” “one thousand and three” until told to stop. This divides the subject’s attention between balancing (standing on one foot) and small muscle control (counting out loud).

The timing for a thirty-second period by the officer is an important part of the One-Leg Stand test. The original research has shown that many impaired subjects are able to stand on one leg for up to 25 seconds, but that few can do so for 30 seconds.

One-Leg Stand is also administered and interpreted in a standardized manner. Officers carefully observe the suspect’s performance and look for four specific clues:

• sways while balancing;

• uses arms to balance;

• hops;

• puts foot down.

Inability to complete the One-Leg Stand test occurs when the suspect:

• puts the foot down three or more times, during the 30-second period;

• cannot do the test.

The original research shows that, when the suspect produces two or more clues or is unable to complete the test, it is likely that the BAC is above 0.10. This criterion has been shown to be accurate 65 percent of the time.

NYSTAGMUS

“Nystagmus” means an involuntary jerking of the eyes.

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