When police officers stop someone on suspicion of drunk driving, they often administer field sobriety tests to determine if the driver is under the influence.

DUI Field Sobriety Test Overview

These tests are not mandatory, but officers are not legally required to inform the driver of this fact. If a driver refuses to take the tests, they may be arrested and taken to the police station for an official breath or blood test. Refusal of an official BAC test is in violation of every state’s “implied consent law” and can result in a longer driver’s license suspension period and the inability to receive a temporary permit to drive during the suspension period.

The National Highway Traffic Safety Administration (NHTSA) has approved three field sobriety tests: the Horizontal Gaze Nystagmus Test, the Walk and Turn Test, and the Stand on One Leg Test. However, it should be noted that the majority of sober people cannot pass these tests.

The validity of the Horizontal Gaze Nystagmus Test depends on the officer’s ability to administer and evaluate the test properly, and human error is a significant factor in this test. The Walk and Turn Test requires divided attention, and 79% of those who fail either part of the test have a BAC of .08% or greater. The Stand on One Leg Test looks for four indicators of impairment and considers a person to have a BAC of .08% or greater if they fail two or more parts; 83% of those who perform this test fail two or more parts.

When performing a field sobriety test, you can be confident that the police cruiser’s dashboard camera will be recording every moment of the process as well.

Here are descriptions and details on the official NHTSA Field Sobriety Tests.

Horizontal Gaze Nystagmus Test

While the NHTSA considers the Horizontal Gaze Nystagmus test as the most precise among the three sanctioned field sobriety tests, the test’s authenticity relies entirely on the officer conducting it correctly and assessing the results accurately. As a result, human error plays a significant role in the overall effectiveness of the HGN test, which one should bear in mind.

In addition, factors such as weather conditions, lighting, and medical conditions of the subject can also affect the accuracy of the HGN test. For instance, a person with a pre-existing medical condition such as a neurological disorder may exhibit nystagmus even when sober, leading to an inaccurate test result.

Despite the HGN test’s widespread use in DUI investigations, it is not infallible and can be challenged in court, highlighting the need for further research and development of objective and reliable sobriety testing methods.

Walk and Turn Test

The NHTSA asserts that 79% of individuals who are unsuccessful in one or both segments of the divided attention test would have a BAC equal to or exceeding 0.08%. The test requires the individual to execute two tasks simultaneously, which can be challenging, particularly when inebriated, as it necessitates concentration, coordination, and balance.

One can only imagine the added stress of attempting to comprehend the officer’s instructions while simultaneously completing the test, particularly under the influence of alcohol, when mental faculties are impaired. Additionally, if an individual fails the test three or more times, the NHTSA deems it a failed test, generally resulting in an arrest for drunk driving.

Stand on One Leg Test

During this test, the officer is searching for four indications: swaying while balancing, utilizing arms for support, hopping to keep balance, and setting the foot down. According to the NHTSA, if you display two or more of these indicators, you are expected to have a BAC of .08% or higher. The NHTSA asserts that 83% of individuals who undertake this test fail at least two components.

Additional DUI resources you may require:

DUI Classes – We provide a complete listing of our state approved DUI & alcohol abuse classes.
DUI Laws – Here you’ll find a comprehensive and detailed explanations of State DUI laws including penalties for each specific offense level.
SR22 Insurance – Here you can find details on everything you need to know about SR22 Insurance.