Field Sobriety Tests to Assess Drunk Driving

Field sobriety tests are conducted by law enforcement officers to assess the level of impairment in a driver suspected of driving under the influence (DUI) or driving while intoxicated (DWI). These tests evaluate the driver's balance, coordination, and attentional control.

The Standard Field Sobriety Test (SFST)

As defined by the National Highway Traffic Safety Administration (NHTSA), the SFST consists of three parts:

1. Horizontal Gaze Nystagmus (HGN): This test examines involuntary eye movements that occur when the eyes are slowly moved from side to side. Officers observe the movement of the eyes for signs of impairment, such as distinct jerking of the eyeball and reduced angle of smooth pursuit.

2. Walk-and-Turn Test: This test measures the driver's ability to walk in a straight line, turn, and return. Indicators of impairment may include starting before instructions are complete, failing to touch heel-to-toe, losing balance during turns, and using arms for balance.

3. One-Leg Stand Test: This test assesses balance and coordination while standing with one foot elevated. Signs of impairment include hopping, placing the foot down early, swaying excessively, and using arms for balance.

Indicators of Intoxication

Certain behaviors and observations may suggest that a person is intoxicated and may fail a field sobriety test:

• Confusion or lethargy
• Impaired walking or lack of coordination
• Excessive talkativeness or euphoria
• Lack of inhibition, slurred speech, or difficulty speaking
• Vomiting or nausea

Possibility of Failing a Field Sobriety Test While Sober

Some individuals may have medical conditions, disabilities, age-related factors, injuries, or medications that can affect their ability to perform these tests successfully, even when sober. Officers typically inquire about any potential reasons for such difficulties and document the driver's response in the arrest report.

Testing for Marijuana and Other Substances

Field sobriety tests indicate signs of intoxication and impairment, but they cannot determine the specific substances consumed. While HGN tests can be used for marijuana intoxication, research suggests it's not a reliable indicator. Officers may also observe the individual's pupils for signs of impairment.

Consequences of Refusing a Field Sobriety Test

Individuals have the right to refuse a field sobriety test or a breathalyzer test; however, such refusal may result in penalties, such as arrest and prosecution. Refusal can also provide additional evidence of impairment.