DWI Enforcement and Standardized Field Sobriety Testing Flashcards

During HGN, how far from the suspect's nose should the officer hold the stimulus?

Answer: 12 to 15 inches

NHTSA standards place the stimulus about 12-15 inches from the nose and slightly above eye level.

How long must the officer hold the stimulus at maximum deviation when checking for distinct and sustained nystagmus?

Answer: At least 4 seconds

The eye is held at maximum deviation for a minimum of four seconds to tell sustained nystagmus apart from end-point nystagmus.

What is the maximum number of HGN clues an officer can observe in one suspect?

Answer: 6

There are three clues per eye, for a total of six.

Before scoring HGN clues, which preliminary check helps rule out a medical cause such as a head injury?

Answer: Checking for equal pupil size and equal tracking

Unequal pupils or unequal tracking can point to a medical condition or injury rather than impairment.

In the HGN test, how many clues indicate a likely BAC of 0.08 or higher?

Answer: 4 or more

NHTSA validation research shows that four or more of the six clues indicates a probable BAC of 0.08 or above.

Vertical gaze nystagmus seen during an HGN evaluation most likely means what?

Answer: The suspect has a high dose of alcohol for that person or certain other drugs

VGN is generally seen with high doses of alcohol for that individual or with certain drugs such as dissociative anesthetics.

When checking 'onset of nystagmus prior to 45 degrees,' about how long should it take to move the stimulus from center to the 45-degree point?

Answer: About 4 seconds

The officer moves the stimulus slowly, taking about four seconds to reach 45 degrees.