Accuracy of Field Sobriety Tests

Accuracy of Field Sobriety Tests: An Overview

Field sobriety tests are commonly used by law enforcement officers to determine whether or not a driver is under the influence of alcohol or drugs. These tests are designed to measure a person’s physical and mental abilities, and the results can be used as evidence in court. However, there has been much debate over the accuracy of these tests. This article will provide an overview of the accuracy of field sobriety tests, including the factors that can affect their reliability.

Factors Affecting the Accuracy of Field Sobriety Tests

Several factors can affect the accuracy of field sobriety tests, including:

1. Officer Training and Experience: The accuracy of field sobriety tests can be affected by the training and experience of the officer administering the test. Officers who are not properly trained or experienced may not administer the test correctly, which can lead to inaccurate results.
2. Environmental Conditions: The accuracy of field sobriety tests can also be affected by environmental conditions, such as poor lighting, uneven terrain, or distractions from passing traffic.
3. Physical Conditions: A person’s physical condition can also affect the accuracy of field sobriety tests. For example, someone who has a medical condition or injury that affects their balance or coordination may perform poorly on the test, even if they are not under the influence of alcohol or drugs.
4. Intoxication Level: Finally, the accuracy of field sobriety tests can be affected by the level of intoxication. In some cases, people who are not under the influence of alcohol or drugs may perform poorly on the test, while others who are highly intoxicated may pass the test.

Accuracy of Individual Field Sobriety Tests

There are three standardized field sobriety tests (SFSTs) that are recognized by the National Highway Traffic Safety Administration (NHTSA): the horizontal gaze nystagmus (HGN) test, the walk-and-turn test, and the one-leg stand test. These tests have been extensively studied, and the NHTSA claims that they are highly accurate. However, research has shown that these tests are not infallible, and they can produce false positives in some cases.

Accuracy of the Horizontal Gaze Nystagmus (HGN) Test

The HGN test involves the officer holding a pen or other object about a foot away from the person’s face and moving it from side to side. The officer observes the person’s eyes to see if there is any involuntary jerking or bouncing, which can be a sign of intoxication. Studies have shown that the HGN test can be highly accurate when administered correctly by a trained officer. However, there are several factors that can affect the accuracy of the test, including medical conditions that affect the eyes, poor lighting, and distractions from passing traffic.

Accuracy of the Walk-and-Turn Test

The walk-and-turn test requires the person to walk nine steps in a straight line, turn around, and walk back nine steps. The officer observes the person’s balance, coordination, and ability to follow instructions. Studies have shown that the walk-and-turn test can be moderately accurate when administered correctly by a trained officer. However, the test can be affected by environmental conditions, physical conditions, and distractions.

Accuracy of the One-Leg Stand Test

The one-leg stand test requires the person to stand on one leg with their other foot about six inches off the ground. The person must count aloud while keeping their balance. The officer observes the person’s balance, coordination, and ability to follow instructions. Studies have shown that the one-leg stand test can be moderately accurate when administered correctly by a trained officer. However, the test can be affected by environmental conditions, physical conditions, and distractions.