What Is a Sobriety Test?

In situations where a police officer suspects a driver of impaired driving, they may conduct field sobriety tests (FSTs) to identify signs of intoxication and establish probable cause for a DWI arrest. It is crucial for drivers to understand their rights when it comes to FSTs. Additionally, they may seek immediate assistance from dedicated DUI defense lawyers at Wentz Law. The FSTs usually involve tasks that would be difficult for an intoxicated driver to perform, and the officer may also measure the suspect’s blood alcohol concentration using an instrument. The ultimate goal is to gather sufficient evidence to support a DWI arrest.

Types of Field Sobriety Tests

Police officers commonly use “standardized” field sobriety tests, or roadside tests, to determine alcohol intoxication. The National Highway Transportation and Safety Administration (NHTSA) has created three standardized sobriety tests that they claim are scientifically valid for identifying alcohol impairment. However, it is important for individuals to understand that these tests are designed to detect impairment, not to prove innocence. The ultimate objective is to use field sobriety tests to establish probable cause for a DWI arrest. In addition to the three standardized tests, some law enforcement officers may administer other types of tests.

Horizontal Gaze Nystagmus (HGN) Test

During the horizontal gaze nystagmus test, the officer will ask you to track the movement of a pen or finger with your eyes. This test is designed to detect an involuntary jerking of the eye, known as nystagmus, which can become more pronounced when a person is impaired. It is important to note that this is just one of the standardized field sobriety tests that officers may use, and it is not a foolproof method for determining impairment. The officer will look for six specific signs, three in each eye, that may indicate impairment.

  • Lack of smooth pursuit where eyes jerk as they focus on tracking movement

  • Distinct and sustained nystagmus at maximum deviation (jerking where the eyes are stretched all the way to the side)

  • Onset of nystagmus occurring prior to reaching a 45-degree angle

If a driver displays four or more of the six potential signs during the HGN test, it may provide probable cause for the officer to arrest the driver for DWI, indicating a BAC above the legal limit. Nonetheless, skilled criminal defense lawyers can challenge the HGN test results using various methods. It is essential to know that certain medical conditions and legal substances, such as caffeine or aspirin, can affect a suspect’s performance on the test. Furthermore, to ensure the scientific validity of the test results, the officer must administer the test with the correct timing and movement and have adequate training.

Walk-and-Turn Test

The Walk and Turn test, also known as the WAT test, is another field sobriety test that law enforcement officers may administer. During this test, you will be asked to perform simple physical movements while following instructions. Specifically, you will be instructed to take nine heel-to-toe steps in a straight line while using an actual line for guidance (although some officers may disregard this protocol and have you walk an imaginary line). After the ninth step, you will be asked to turn as directed by the officer and walk back to your starting point. The officer is looking for eight clues, only two of which are needed to indicate impairment and a BAC above the legal limit for purposes of DWI:

  • Inability to maintain balance while listening to the instructions

  • Beginning before the instructions are finished

  • Stopping while walking to regain balance

  • Failing to touch heel-to-toe

  • Stepping off the line

  • Using arms to balance

  • Making an improper turn

  • Taking an incorrect number of steps

One-Leg-Stand Test

During the one leg stand test, also known as the OLS test, you need to raise one foot approximately six inches off the ground and count out loud until the officer instructs you to put your foot down. The officer is looking for four potential signs of impairment, and two of these signs are enough to indicate that your BAC is above the legal limit:

  • Swaying while balancing

  • Using arms to balance

  • Hopping to maintain balance

  • Putting the foot down

Even if you perform poorly on the OLS or WAT tests, skilled DUI defense attorneys can challenge the results using various strategies. Police officers are required to follow the NHTSA guidelines and be adequately trained in administering these tests. Furthermore, medical conditions can impair a suspect’s ability to walk or balance, which can affect their performance on these tests. Additionally, environmental factors such as weather, location, surroundings, as well as personal factors like weight and clothing choice, can all play a role in a poor performance on these tests.

Other Field Sobriety Tests

After completing the standardized tests, if the officer suspects DWI, they may proceed with other field sobriety tests or arrest you based on probable cause. It’s worth noting that some of these tests are not approved by NHTSA and lack scientific validation, yet police and courts may still use them.

Other field sobriety tests that an officer may administer outside of the three standardized tests discussed above include:

  • The Romberg balance test

  • Finger-to-nose test

  • Reciting parts of the alphabet

  • Finger counting by touching thumb to fingers also known as the “Finger Dexterity Test”

  • Counting backwards

If you were given any of these field sobriety tests, you should not hesitate to contact us for help.

Portable Breath Test

When administering other sobriety tests, the officer may also request that you take a portable breath test (PBT). However, it’s important to note that a PBT cannot be used as evidence of impaired driving in court. It can only be used, in combination with other field sobriety tests, to establish probable cause for arrest. If you consent to taking a PBT, you’ll be asked to blow into the instrument twice, with the second blow occurring a few minutes after the first.

If the results of a PBT are challenged, a criminal defense lawyer may have ample opportunities to attack them. The PBT instrument must be properly documented, maintained, and calibrated. Like other field sobriety tests, the administering officer must be adequately trained and follow specific guidelines.

Field Sobriety Tests and Your Legal Rights

Before a police officer can pull over a motorist, they must have reasonable suspicion that the driver is impaired or has committed a traffic violation. Law enforcement can request that the driver take field sobriety tests, but the driver has the right to refuse without any consequences. Refusing a field sobriety test is not strong evidence against the driver and there are valid reasons for refusing, including distrust of the police. However, if a driver is arrested for DWI, they cannot refuse a chemical test to measure their blood alcohol content without facing penalties. Refusal to submit to a chemical analysis of breath results in a one-year revocation of the driver’s license. In addition, if probable cause is established, police can obtain a warrant from a magistrate to draw the driver’s blood for chemical analysis.

If a driver consents to taking sobriety tests before being arrested for DWI, the officer may administer one or more standardized NHTSA field tests or other sobriety tests to test their physical and mental abilities and determine if their BAC is above the legal limit. The standardized field sobriety tests must be administered systematically, and the officer must look for specific responses. However, this doesn’t necessarily mean that they administer the tests correctly.

Can the Test Results Be Used in Court?

Although law enforcement considers field sobriety tests as reliable indicators of alcohol impairment and a blood alcohol content above the legal limit, even the three standardized tests can result in errors. For these tests to be accurate, officers must receive proper training and adhere to strict guidelines. If a driver performs poorly on these tests, their results can be challenged and potentially suppressed. If the arrest is suppressed, it can be challenging for a prosecutor to establish probable cause for the arrest, and any evidence obtained after the arrest will also be suppressed. In such a situation, no evidence will remain from which a court can convict the driver of DWI.

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If you have any further questions about the DWI process (have a look at our FAQs) or need something case specific, feel free to reach out. I am always happy to review a case and give you honest feedback on where you stand and how it should be addressed. I handle DWI defenses out of the following North Carolina areas: All of Pender County (Hampstead, Topsail, Burgaw, Surf City, Atkinson) and New Hanover (Wilmington, Wrightsville Beach, Carolina Beach, Ogden, Monkey Junction).

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