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Field Sobriety Tests in Washington: What is HGN?

Horizontal Nystagmus is one of three common field sobriety tests currently administered by law enforcement officers across Washington State. Nystagmus is an involuntary rapid movement of the eyeball, which may he horizontal, vertical, or rotatory. An inability of the eyes to maintain visual fixation as they are turned from side to side (in other words, jerking or bouncing) is known as horizontal gaze nystagmus, or HGN. Some investigators believe alcohol intoxication increases the frequency and amplitude of HGN and causes HGN to occur at a smaller angle of deviation from the forward direction.

In administering the horizontal gaze nystagmus test, an officer will look for the three following clues in each eye: (1) lack of smooth pursuit, (2) distinct nystagmus at maximum deviation, and (3) onset of nystagmus prior to 45 degrees. The test is performed in the same manner, regardless of whether the officer is testing for alcohol impairment or drug impairment. The test merely requires the Drug Recognition Expert to observe the driver’s eyes to detect involuntary jerking.

The Washington Supreme Court held in Baity, that the field sobriety tests for nystagmus are generally accepted in the relevant scientific communities as a means of indicating ingestion of certain drugs and are admissible as evidence that a person was intoxicated on drugs. A properly qualified expert may use the 12-step protocol and the chart of categories of drugs to relate an opinion about the presence or absence of certain categories of drugs in a suspect’s system. Thus, police officer, if qualified and there is proper foundation, may testify that an HGN test can show the presence of alcohol but not the specific levels of intoxicants.

Contrastingly, the New Mexico Court of Appeals also reviewed HGN under Frye and concluded, “that the HGN has not been scientifically validated as a direct measure of impairment.” This decision was notable because it had before it the testimony and FST validation studies of Dr. Marcelline Burns, the researcher who was contracted by the National Highway Traffic Safety Administration (NHTSA) to study, develop and determine the efficacy of a FST battery. Thus, notwithstanding its general acceptance in some relevant scientific communities, it would seem that the admissibility of HGN varies widely from state to state.

The National Highway Traffic Safety Administration’s research findings have been questioned with regard to incidence of false positives. It has been stated that “as most optometrists know, many suspects will have jerky eye movements even with a 0.00% BAC.” Some 50% to 60% of all individuals exhibit gaze nystagmus indistinguishable from alcohol gaze nystagmus if they deviate their eyes more than 40 degrees to the side. The test as proposed by the National Highway Traffic Safety Administration requires the subject to deviate his or her eyes 45 degrees to the side. This would seem to indicate that the National Highway Traffic Safety Administration HGN test should result in a greater number of false positives.

It would seem that many factors make HGN testing unreliable, including the possibility of false positives and other possible physiological causes. However, the courts have held that none of these factors undercut the basis of the test—that intoxicated people exhibit nystagmus. Furthermore, the factors noted apply equally to the other field sobriety tests that are routinely used in DUI arrests and all of those factors can be shown through cross-examination, and they therefore go to the weight of the evidence, rather than its admissibility.

Remember, field sobriety tests are voluntary. If you have been arrested for DUI or are facing other similar charges, contact Blair & Kim, PLLC today to see how a criminal defense attorney might be able to help you.