Field Sobriety Tests in Prince William County DUI Stops

Field sobriety tests are physical tests administered by the police which are designed to assist them in determining whether a driver is under the influence of alcohol, drugs, or a combination of the two, to a degree that their ability to safely operate a motor vehicle is significantly impaired. There are a large number of them that are used by various police forces, but all of them have the same purpose, which is to elicit incriminating evidence from the driver.  The three most common tests are the Horizontal Gaze Nystagmus or “HGN,” the 9 step walk and turn and the one legged stand, which you can find more information on below. If you are asked to take a field sobriety test, it may be in your best interest to consult with a Prince William County DUI lawyer to discuss your case.  Call today to learn more.

What is the Horizontal Gaze Nystagmus Test?

The Horizontal Gaze Nystagmus test involves a police officer holding a pen or other object that’s in front of the driver’s eyes and then moving it slowly from left to right and/or up and down in an effort to determine whether the eyes are smoothly pursuing the object especially at the periphery of vision, or whether the eyes are bouncing or having difficulty tracking the object.

This test is one part of a three-part test which was developed by the National Highway Safety Transportation Board to assist officers with DUI. However, under Virginia law and in most jurisdictions it has been held that the Horizontal Gaze Nystagmus is in fact a medical test and that police officers are not qualified to testify as to the results of that test.  Nevertheless, it is often used in an officer’s probable cause determination at the time of arrest.

What is the 9-Step Walk-and-Turn Test?

The nine-step walk-and-turn test is what people classically think of as the walk-the-line test that happens at the side of the road. It involves a number of actions including listening to the officer while instructions are given, standing in a certain position and waiting to begin until commanded, and then touching heel to toe for nine steps while keeping one’s arms at one side, turning on one foot and then taking nine steps back all the while the individual is asked to count aloud the number of steps that they are taking.

This is also one part of a three-part test developed by the National Highway Safety Transportation Board. The officer who is administering the test is looking for a number of cues or in other words, they are looking for particular kinds of mistakes that can be made and if a certain number of those mistakes are made, then they would deem the person to have failed the test.

What is the One-Legged Stand Test?

The one-legged stand is the final test of the three-part test series. It involves a person standing on one foot raising their other leg with the toe pointed to the ground inclining the head downward to look at the toe and then holding the arms to the sides of the body while counting, typically up to thirty by one thousand. Again, this is a test where the officer is looking for a number of particular cues including whether the person loses balance, puts their foot down, whether they start when they’re told to start, or whether they are able to count correctly. If a certain number of cues are found, then the officer will deem the individual to have failed the test.