Prince William County Field Sobriety Tests

Field sobriety tests are semi-scientific tests that law enforcement customarily administer to DUI suspects during a traffic stop to gauge whether the suspect is over or under the legal limit of impairment. All of these tests are used to assess legal v. non-legal levels of impairment to driving behavior, whether due to alcohol, drugs, or a combination thereof. However, some field sobriety tests are specially designed to test for drug impairment only.

Read below to learn more about Prince William County field sobriety tests. And if you have been charged with a DUI, you should get in touch with a dedicated DUI lawyer today.

Horizontal Gaze Nystagmus Test

The horizontal gaze nystagmus test (HGN) is an eye-based divided attention National Highway Traffic Safety Administration (NHTSA) test that is designed to measure the involuntary jerking movement that a person’s eyes will exhibit due to intoxication when made to move from side to side while following a precise stimulus that the officer moves back-and-forth in front of a suspect’s face. There is also a vertical gaze nystagmus test that is sometimes done by moving a suspect’s eyes up and down but is more common for situations when drug intoxication is suspected.

Walk and Turn Test

The walk and turn test is a performance-based divided attention NHTSA test that is designed to assess a person’s awareness, memory, coordination, and balance at levels above and below the legal limit. It involves a suspect maintaining a particular foot stance while receiving instructions and demonstrations from the officer, after which a suspect will be expected to take nine heel-to-toe steps forward on a real or imaginary straight line, followed by a specific kind of foot turn, and ending with a return series of nine heel-to-toe steps back to the original starting position. Suspects will be expected to maintain their balance at all times, stay on the line, and count their steps out loud while looking at their feet.

One Leg Stand Test

Another one of the field sobriety tests that officers in Prince William County use is the one-leg-stand test. This test is a performance-based divided attention NHTSA test that is primarily designed to assess a person’s attention span and balancing capabilities below or above the legal limit. Suspects must maintain a controlled stance while an officer instructs and demonstrates about how to do the test, which consists of raising either foot six inches off the ground for approximately 30 seconds while balancing on the other foot/leg. Suspects will be expected not to lose their balance, or put their foot down before the officer tells them to stop the test.

Administering Field Sobriety Tests

All field sobriety tests need to be administered in a correct and understandable way to an individual in order to constitute valid evidence of intoxication. Many field sobriety tests further need to be demonstrated and interpreted in very particular ways that correspond with scientific standardization of test administration, and science-based training of the administering officer(s). Also, the core standardized tests have formal or informal administration limitations in terms of where they are performed, under what physical/medical/atmospheric conditions they are performed, and at what age a person is performing them. For more information about administering field sobriety tests in Prince William County, contact a knowledgeable defense lawyer.

What is the Weight of These Tests in a DUI Case?

Certain field sobriety tests are more probative than others depending on whether they have been scientifically developed and standardized by the federal government for use by state law enforcement. However, all the tests are of situational probative value depending on the understanding and perception of a judge or jury assessing the factual evidence in a case. Some tests will only establish that the officer had reasonable suspicion to search or detain a suspect for DUI, while others will rise to the level of probable cause to arrest the suspect for DUI, or even beyond a reasonable doubt to convict a suspect of DUI.

Can a Person Refuse to Perform Field Sobriety Tests in Prince William County?

An individual can always refuse to perform Prince William County field sobriety tests. That being said, the prosecution will likely attempt to present a person’s refusal as indirect evidence of intoxication. However, that alone is not sufficient to prove someone guilty of a DUI. Call an accomplished attorney today for more information.

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