Massachusetts DWI DUI OUI Field Sobriety Test Police Training Manual

Based on the original research, if you observe four or more clues it is likely that the suspect’s BAC is above 0.10. Using this criterion you will be able to classify about 77% of your suspects accurately. This was determined during laboratory and field testing and helps you weigh the various field sobriety tests in this battery as you make your arrest decision.

Vertical Gaze Nystagmus

The Vertical Gaze Nystagmus test is simple to administer. During the Vertical Gaze Nystagmus test, look for jerking as the eyes move up and are held for approximately four seconds in the upmost position.

1. Position the stimulus horizontally, about 12—15 inches in front of the suspect’s nose.

2. Instruct the suspect to hold the head still, and follow the object with the eyes only.

3. Raise the object until the suspect’s eyes are elevated as far as possible.

4. Hold for approximately four seconds.

5. Watch closely for evidence of jerking.

Horizontal and Vertical Gaze Nystagmus can be observed directly and do not require special equipment. You will need a contrasting stimulus for the suspect to follow with their eyes. This can be the tip of your index finger, penlight, or pen. The stimulus used should be held slightly above eye level, so that the eyes are wide open when they look directly at it. It should be held approximately 12— 15 inches in front of the nose. Remain aware of your position in relation to the suspect at all times.

OFFICER SAFETY IS THE NUMBER ONE PRIORITY ON ANY
TRAFFIC STOP.

Procedures for Walk-and-Turn Testing

1. Instruct ions Stage: Initial Positioning and Verbal Instructions

For standardization in the performance of this test, have the suspect assume the heel-to-toe stance by giving the following verbal instructions, accompanied by demonstrations:

• “Place your left foot on the line” (real or imaginary). Demonstrate.

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