Field Sobriety Tests Explained

Field sobriety tests are a series of physical and cognitive assessments law enforcement officers use to determine if a driver is under the influence of alcohol or drugs. These tests serve as crucial tools in DUI/DWI investigations, providing officers with observable indicators of impairment. While some tests are standardized and backed by federal guidelines, others are non-standardized and vary in their application and reliability.

Standard Field Sobriety Tests (SFST) Overview

The National Highway Traffic Safety Administration (NHTSA) has established a set of Standard Field Sobriety Tests (SFSTs) that are widely used across the United States. These tests are designed to be administered consistently and have been scientifically validated to some degree. The SFST battery consists of three components:

1. The Horizontal Gaze Nystagmus test
2. The Walk and Turn test
3. The One-Leg Stand test

Officers are trained to administer these tests in a specific sequence and look for particular impairment indicators. The results of these tests, combined with other observations, help officers establish probable cause for a DUI arrest.

Horizontal Gaze Nystagmus (HGN) Test

The Horizontal Gaze Nystagmus test is based on the observation of involuntary jerking of the eyes as they gaze to the side. In this test, an officer asks the subject to follow a small object (like a pen or flashlight) with their eyes while keeping their head still.

Officers look for three indicators in each eye:

1. Lack of smooth pursuit
2. Distinct nystagmus at maximum deviation
3. Onset of nystagmus before 45 degrees

While the HGN test has a scientific basis, its accuracy in field conditions and officers’ ability to administer and interpret it correctly has been debated in legal circles.

Walk and Turn (WAT) Test

The Walk and Turn test is a divided attention test that assesses both physical ability and cognitive function. The subject is instructed to take nine heel-to-toe steps along a straight line, turn in a specific manner, and return in the same manner in the opposite direction.

Officers look for eight indicators of impairment:

1. Cannot keep balance while listening to instructions
2. Begins before instructions are finished
3. Stops while walking
4. Do not touch heel-to-toe
5. Steps off the line
6. Uses arms to balance
7. Improper turn
8. Incorrect number of steps

Factors such as physical fitness, age, and certain medical conditions can affect performance on this test.

One-Leg Stand (OLS) Test

The One-Leg Stand test requires the subject to stand on one leg with the other foot approximately six inches off the ground for 30 seconds. The subject is instructed to count out loud by thousands (One thousand-one, one thousand-two, etc.) until told to put their foot down.

Officers look for four leading indicators of impairment:

1. Swaying while balancing
2. Using arms to balance
3. Hopping
4. Putting the foot down

Like the Walk and Turn test, various physical and environmental factors can affect performance on the One-Leg Stand.

Non-Standardized Field Sobriety Tests

In addition to the standardized tests, officers may use various non-standardized tests. These can include:

• Finger-to-nose test
• Alphabet recitation
• Counting backwards
• Romberg balance test

These tests need more rigorous standardization and validation of the SFSTs. As a result, their admissibility in court and weight as evidence can vary significantly depending on the jurisdiction and circumstances.

Accuracy and Reliability of Field Sobriety Tests

NHTSA studies have claimed high accuracy rates for the standardized field sobriety tests when properly administered. However, some researchers and legal experts have challenged these claims.

Factors that can affect the reliability of field sobriety tests include:

• Officer training and experience
• Environmental conditions (weather, lighting, road surface)
• The subject’s physical condition and medical history
• Nervousness or anxiety of the subject

Critics argue that field sobriety tests can produce false positives, potentially leading to unjustified arrests.

Your Rights During Field Sobriety Testing

It’s important to understand that you have the right to refuse field sobriety tests in most jurisdictions. However, refusal may have consequences, such as automatic license suspension in some states.

If you choose to undergo the tests, remember to:

• Listen carefully to instructions
• Inform the officer of any medical conditions that might affect your performance
• Remain calm and respectful

Regardless of your decision, it’s crucial to interact respectfully with law enforcement while protecting your rights.

Field Sobriety Tests in the DUI Arrest Process

Field sobriety tests play a significant role in the DUI arrest process. Officers use the results of these tests, along with other observations (such as the odor of alcohol, slurred speech, or erratic driving), to establish probable cause for a DUI arrest.

While field sobriety tests are often vital in an officer’s decision to make an arrest, they are typically not the end of the investigation. Most jurisdictions require chemical tests (breath, blood, or urine) to determine the actual blood alcohol concentration or presence of drugs.

Challenging Field Sobriety Tests: DUI Defense Strategies

DUI defense attorneys often focus on challenging the validity and reliability of field sobriety tests. Common defense strategies include:

1. Questioning the proper administration of the tests: Defense attorneys may argue that the officer didn’t follow appropriate procedures or gave unclear instructions.
2. Highlighting external factors: Environmental conditions, such as uneven surfaces or poor lighting, can be presented as reasons for poor test performance.
3. Presenting alternative explanations: Medical conditions, nervousness, or physical limitations might explain a suspect’s inability to perform well on these tests.
4. Challenging the officer’s qualifications: The defense may question the officer’s training and experience in administering and interpreting field sobriety tests.
5. Arguing against the scientific validity: Attorneys may challenge the scientific basis and reliability of tests, especially for non-standardized tests.

Field sobriety tests are a common and essential tool in DUI investigations, but they are subject to controversy. While they can provide valuable information to law enforcement officers, they are not infallible indicators of impairment. Understanding the nature of these tests, your rights, and potential defense strategies is crucial for anyone who might find themselves subjected to them.

Remember, the best way to avoid issues with field sobriety tests is to never drive under the influence of alcohol or drugs. However, suppose you find yourself arrested for DUI based on field sobriety tests. In that case, it’s essential to seek experienced legal counsel to ensure your rights are protected and all aspects of your case, including the administration and interpretation of these tests, are thoroughly examined.