What is a Field Sobriety Test?

A Standard Field Sobriety Test (SFST) encompasses three tests performed by law enforcement during a traffic stop to determine whether a driver is impaired or not. All three of these tests have been shown in studies to be problematic and result in many false positives. The tests are:

Horizontal Gaze Nystagmus (HGN) Test

HGN refers to an involuntary jerking of the eyeball as the eyes gaze towards the side and rotate at high angles. When a person is impaired by alcohol, HGN can be exaggerated and may occur at less of an angle. If you have been inebriated before, you may be familiar with this as it makes it more challenging to track moving objects, especially ones that are not directly in front of you. If you’re pulled over to take an HGN test, you’ll likely be asked to follow an object with your eyes, typically something the officer has on hand such as a pen, while the officer looks at your eyes for evidence of exaggerated HGN (they may shine a flashlight on your eyes if you were pulled over at night).

According to the National Highway Transportation Safety Administration (NHTSA), the HGN test is only about 77% reliable in determining an illegal BAC.

horizontal gaze nystagmus (HGN) test being administered
Police Officer Administering HGN Test
person performing the walk and turn test
Person Performing the Walk-and-Turn Test

Walk-and-Turn Test

Law enforcement would direct the subject to take nine steps, touching heel-to-toe, along a straight line. After taking the steps, the suspect must turn on one foot and return in the same manner in the opposite direction. The examiner looks for about 8 indicators of impairment if the subject:

  • cannot keep balance while listening to instructions
  • begins before the instructions are finished
  • stops while walking to regain balance
  • does not touch heel-to-toe
  • uses arms to balance
  • steps off the line
  • takes an incorrect number of steps
  • makes an improper turn

Law enforcement are instructed to evaluate for themselves if any of these indicators are significant and typically would suspect impairment if two or more are present. This test is even less reliable than HGN tests, with studies showing about 68% accuracy in determining if somebody is under the influence of alcohol. As you could suspect with the list of indicators, you can make any of these mistakes under nervousness and stress or due to a disability.

One-Leg Stand Test

The last field sobriety test is the most basic in instructions but can be difficult for people who do not have great balance. You will likely be asked to raise either foot about 6 inches off the ground keeping your bottom foot parallel to the ground. You will be asked to do this while looking at your foot and keeping both legs straight and arms at your side, and then counting from 1 to 30 out loud, saying “One thousand one, one thousand two, . . . “ and so on until the officer times you 30 seconds. Officers will look to see if you swap, raise your arms, hop, or put your foot down.

Like the previous test, nervousness, disability and just generally having bad balance can cause you to fail this test, and its accuracy is only about 65%. 

person taking field sobriety test
Person Performing the One-Leg Stand Test in Front of a Police Officer

Can I Refuse to Take These Tests?

The short answer is — yes, at least in North Carolina.

You may have been misled to believe that there are direct penalties you can face for refusing a field sobriety test at a sobriety checkpoint or while being pulled over, but this is not actually the case in North Carolina. You are not required by the law in North Carolina to take any form of roadside testing, and we recommend that you refuse to do so even if you feel confident that you would not have a high enough blood alcohol content. This includes refusing to take a roadside preliminary breath test, which you can do so without consequence.

What Can Happen When I Refuse the Tests?

Refusing these tests will likely prompt the officer to arrest you for more precise testing at the police station. Unlike refusing to take the SFST tests on the roadside, refusing tests at the police station will result in more serious penalties, including an immediate revocation of your driver’s license for one year. This is because North Carolina and the rest of the United States has what is known as Implied Consent Laws. These laws indicate that by being a licensed driver and using your vehicle, you consent to testing with a certified breathalyzer or to give a requested blood sample if you have been arrested. When asked to take testing at the station (or possibly a mobile testing unit), you do have the right to call a witness, such as a friend or lawyer), to be present and oversee the procedure.

What Should I do if I get Pulled Over?

We strongly suggest that you refuse the field sobriety test and any form of roadside testing, but do not try to resist law enforcement if they try to take you to the station for further testing. When you arrive at the station, make sure to call a witness, preferably an experienced DWI defense attorney before taking any tests.

Getting arrested instead of taking a field sobriety test may sound like strange advice, as you will still have to take a different test in the end and getting arrested is much more time consuming. However, due to the lack of accuracy in SFST’s and the time spent following law enforcement instructions without the presence of your lawyer, it is best to submit to testing after getting arrested. Many people believe they can simply train themselves to pass the field sobriety tests, but it is crucial to recognize that any balance or gaze training you can perform on your own will not account for the circumstances of getting pulled over. The stress of the situation alone can cause you to fail, or you may perform well but the law enforcement officer can decide that you seemed impaired anyway. Do not take that risk — just avoid dealing with law enforcement directly at much as possible and seek legal counsel if necessary.