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Field Sobriety Tests North Carolina

Field sobriety tests are used to gauge a driver’s cognitive and physical functions to determine the driver’s level of impairment. Field tests are the tools law officials use to find out if drugs and/or alcohol are impairing a driver. Police can use the results of these tests as evidence against the driver during a driving while impaired (DWI) trial. In North Carolina, a driver has the right to refuse a field sobriety test. While the government can make the argument that you refused the field tests because you knew you were drunk, there are no ramifications like there are for refusing the EC/IR-II breath test at the station.

The Standardized Field Sobriety Tests (SFSTs)

According to the National Highway Traffic Safety Administration (NHTSA), there are three scientifically validated Standardized Field Sobriety Tests. These tests are the Horizontal Gaze Nystagmus (HGN), Walk and Turn, and One Leg Stand.

Horizontal Gaze Nystagmus

HGN is the involuntary jerking of the eyes as they gaze toward the sides. The HGN test is purportedly the most reliable of the three SFSTs. The idea is that the eyes of a sober person move smoothly as they gaze toward the sides – like windshield wipers on a wet windshield. However, when a person is impaired on certain substances, the eyes jerk as they gaze toward the sides – like windshield wipers on a dry shield. The three drug categories that cause HGN are CNS Depressants, Inhalants, and Dissociative Anesthetics. In addition to being involuntary the person experiencing the nystagmus is usually unaware that the jerking is happening.

When administering the HGN test, the subject is instructed to stand with feet together, hands at sides, hold the head still, and follow the motion of a stimulus with the eyes only. The stimulus may be the tip of a pen, a penlight, or the officer’s finger. The maximum total number of clues the officer is looking for on this test is six – three in each eye. The minimum number of clues officers are looking for to indicate impairment is four out of six. The original research conducted by the Southern California Research Institute (SCRI) showed that the HGN test was 77% accurate at detecting subjects at or above a 0.10 BAC.

The issue with the HGN test, is that even if it is a scientifically validated test, it is a very precise test that is frequently administered and interpreted incorrectly by many officers. It is necessary to have an attorney by your side who is familiar with the intricacies of the HGN and other SFSTs. Experienced lawyers will be able to spot if the officer in your case administered and interpreted the HGN correctly.

Walk and Turn Test

The Walk and Turn and the One Leg Stand are known as divided attention tests. The tests are designed to mimic the divided attention necessary to safely operate a motor vehicle. The Walk and Turn test consists of two stages: the instruction stage and the walking stage.

In the instructions stage, the subject must stand with their feet in a heel to toe position, keep their arms at their sides, and listen to the instructions. In the walking stage, the subject takes nine heel to toe steps, turns in a prescribed manner, takes nine heel to toe steps back, counts the steps out loud, and watches their feet. During the turn, the subject keeps their front foot on the line, turns in a prescribed manner, and uses the other foot to take several small steps to complete the turn. Officers administering the Walk and Turn test observe the subject’s performance for a total of eight clues:

  • Cannot keep balance while listening to instructions
  • Starts too soon
  • Stops while walking
  • Does not touch heel to toe
  • Steps off the line
  • Uses arms to balance
  • Improper turn
  • Incorrect number of steps

Officers are looking for a minimum of two out of the total eight clues for the test to be indicative of impairment. The original research conducted by the SCRI showed that this tests was 68% accurate at detecting subjects at or above a 0.10 BAC. There are several issues with the reliability of this test. Inexperienced officers often give incorrect instructions and often misinterpret clues observed. Additionally, the surface level where the test is given, the weather during the test, and the age and weight of the subjects can all affect a person’s performance on the test.

One Leg Stand

The final SFST, One Leg Stand also consists of two stages: an instruction stage and a balance and counting stage. In the instruction stage, the subject must stand with their feet together, keep their arms at their sides, and listen to instructions. In the balance and counting stage, the subject must raise either foot with the raised foot approximately six inches off the ground, with both legs straight and the raised foot parallel to the ground. While looking at the elevated foot, count out loud in the following manner: “one thousand one”, “one thousand two”, “one thousand three” until told to stop. This is designed to divide the subject’s attention between balancing (standing on one foot) and small muscle control (counting out loud). The officer will then time the subject for thirty seconds. The officer is looking for the following four clues during this test:

  • Sways while balancing
  • Uses arms to balance
  • Hopping
  • Puts foot down

The original research conducted by the SCRI showed this test was 65% accurate at detecting subjects at or above a 0.10 BAC. Like the walk and turn, inexperienced officers often give incorrect instructions and often misinterpret clues observed. Additionally, the surface level where the test is given, the weather during the test, and the age and weight of the subjects can also affect a person’s performance on the test.

Portable Breath Test

In addition to these tests, officers are trained to use a preliminary breath test (PBT) when they’re investigating you on the side of the road. Per NHTSA guidelines, the PBT should be given only after the three SFSTs have been administered. The PBT should only be used to confirm the chemical basis of the subject’s impairment. The PBT merely corroborates other evidence by demonstrating that the suspicion of alcohol impairment is consistent with the officer’s observations of the subject’s mental and physical impairment. The PBT is a highly unreliable tool, for this reason, it’s numerical results are not allowed into evidence – only whether the breath samples were positive or negative for alcohol. If there are any issues with the calibration or the administration of the PBT, then any PBT evidence will be excluded from your trial.

Field Sobriety Tests as Evidence During Trial

In cases where the prosecution has evidence of a driver’s impairment from a field sobriety test, the defense may be able to block that testimony. This is a best-case scenario for the accused driver, as it means the courts will not consider the results of the field sobriety tests as evidence. Field sobriety tests may be inadmissible in court for many reasons, including:

  • The tests were non-standard. There are many possibilities for roadside tests an officer may ask a driver to perform. Common tests include the one leg stand test, the horizontal gaze nystagmus test, and the walk-and-turn test. These are considered “standardized” or reliable field sobriety tests in North Carolina. In some situations, an official may also include non-standardized tests, such as saying reciting the alphabet. In these cases, the defense may be able to demonstrate that evidence from the tests is inadmissible.
  • The driver failed the tests for other reasons. There are many reasons a driver may not be able to pass a field sobriety test even while sober. A drowsy driver or someone with a medical condition, such as a knee injury, may find it difficult to balance. Drivers with allergies may have bloodshot eyes or flushed faces. Prior to field testing, a law official should ask if you have a condition that may affect your ability to perform well on the tests.
  • The officer improperly administered the tests. There are certain preliminary things a law enforcement official must do before giving a field sobriety test. The officer must have proper training to do said tests, and cannot force the driver to take the tests. A driver has the right to refuse field sobriety tests in NC without penalty.

A qualified DWI attorney in Raleigh may be able to challenge the results of field sobriety tests based on one of the above or other reasons. If successful, the court will rule that evidence from the tests as inadmissible – strengthening the driver’s case.

Should You Refuse a Field Sobriety Test?

In Raleigh and throughout North Carolina, you are fully within your rights to decline any field sobriety tests and any roadside portable breath test (PBT) without penalty . You may also decline a EC/IR-II Breathalyzer test, but declining this type of test can automatically result in a 12-month license suspension if the officer has probable cause to believe you are impaired. While refusing the tests means the prosecution won’t have this type of evidence against you, the prosecution can use the fact of your refusal as substantive evidence of a guilty conscience.

If you know you won’t be able to complete the tests, even if you’re 100 percent sober, it’s better to refuse to take them than to explain why you failed them to the courts. It’s generally a wiser decision to try to argue a stance of refusing the tests because you know they are unreliable or because you knew you weren’t driving impaired than to try to defend yourself in lieu of failed sobriety tests.

Speak With a Competent Defense Attorney in Raleigh

As soon as a law enforcement official pulls you over and requests that you take a field sobriety test, you have the right to call an attorney. In these situations, call the Scharff Law Firm at (919) 457-1954 for on-scene legal advice.