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DUI Field Sobriety Tests:
The Horizontal Gaze Nystagmus (HGN) Test

HGN refers to the involuntary jerk of the eyeball as it moves toward one side. Persons who exhibit HGN are not aware of such jerking. The officer administering the test uses a stimulus such as a pen, penlight, or fingertip and checks for three clues in each eye for a total of six clues (i.e. the maximum number of clues in one eye is three).

The first clue is (1) “lack of smooth pursuit.” Lack of smooth pursuit is present if the eye jerks noticeably while moving from side-to-side. The second clue is (2) “distinct and sustained nystagmus at maximum deviation.” Distinct and sustained nystagmus is present if the eye jerks distinctly when it is moved to the side as far as possible. The third clue is (3) “onset of nystagmus prior to 45-degrees.” This type of nystagmus is present if the eye begins to jerk as it moves to the side prior to a 45-degree angle.

According to research conducted by the National Highway Traffic Safety Administration (NHTSA) four or more clues has correlation with a blood alcohol concentration of .10 or more. NHTSA believes the test is 77% accurate. However, the NHTSA studies have not been adequately peer reviewed. The accuracy of HGN is also dependent upon proper administration of the test and proper scoring. There are also other variables that can impact the validity of the test.

In State v. Baity, the Washington Supreme Court analyzed HGN evidence in the context of Drug Recognition Expert (DRE) testing. The court held that HGN testing is scientific in nature and satisfies the Frye test for admissibility of scientific evidence. State v. Baity, 140 Wash.2d 1, 13, 991 P.2d 1151, 1159 (2000); id., at 14. But this holding rested on certain assumptions including uniformity and adherence to standards. See Baity, 140 Wash.2d at 5-6 (describing DRE education, field training, examination, certification) id., at 13 (noting NHTSA recommendation and that testing is based on training, principles, and observation of objective indicators). The Baity court was also careful to impose certain foundational requirements:

…the DRE evidence must also satisfy the predicate two-part inquiry under ER 702-whether the witness qualifies as an expert, and whether the testimony would be helpful to the trier of fact-before the evidence is admissible. A proper foundation for DRE testimony would include a description of the DRE’s training, education, and experience in administering the test, together with a showing that the test was properly administered.

Baity, 140 Wash. 2d at 18. Courts have held that the limitations on HGN evidence set forth in Baity have equal application to cases where a DUI charge is based on alcohol impairment. See State v. Quaale, 182 Wash.2d 191 (2014); State v. Quaale, 177 Wash.App. 603, 730 (Wash. Ct. App. 2013) (“Baity involved challenges to HGN testing for impairment from drug use rather than alcohol, but its discussion of limitations on the type of opinion that may be offered have equal application….”); State v. Koch, 126 Wash.App. 589, 597, (Wash. Ct. App. 2005) (“The district court correctly ruled that under State v. Baity…a witness may testify that an HGN test can show the presence of alcohol but not the specific levels of intoxicants.”). Therefore, prior to the admission of HGN evidence the court should be satisfied that (1) the officer who administered the test is qualified as an expert; and (2) the officer properly administered the HGN test.

Even if the HGN test is deemed admissible the officer’s testimony should be limited. The Baity court also held:

…an officer may not testify in a fashion that casts an aura of scientific certainty to the testimony. The officer also may not predict the specific level of drugs present in a suspect. The DRE officer, properly qualified, may express an opinion that a suspect’s behavior and physical attributes are or are not consistent with the behavioral and physical signs associated with certain categories of drugs.

Baity, 140 Wash.2d at 17-18, 1160-1161. Again, these limitations should also have equal application to HGN evidence where a DUI charge is based on alcohol impairment. Quaale, 177 Wash.App. at 612; see Koch, 126 Wash.App. at 597. For example, in Koch, Division Two determined “that under State v. Baity, 140 Wash.2d 1, 17-18, 991 P.2d 1151 (2000), a witness may testify that an HGN test can show the presence of alcohol but not the specific levels of intoxicants.”  More recently, in Quaale, the Washington Supreme Court held that a defendant was denied his right to a fair trial when a trooper testified that there was “no doubt” a defendant was impaired due to alcohol based on HGN test results. Quaale, 182 Wash.2d at 198-199. Therefore, even if HGN evidence is admitted, the officer may not claim his observations prove a certain alcohol concentration or establishes “impairment.”

HGN may also be attacked. HGN can be present for reasons other than alcohol. Expert witness testimony may be used to undermine HGN evidence. The officer’s observations, interpretation of his observations, and scoring may also be challenged.  Detailed Cross Examination during trial, based on the above factors, is the final weapon we can use to attack this “evidence”.

The DUI attorneys at Platt, Thompson and Buescher serve Oak Harbor, Island County, Bellingham, Burlington, Mt. Vernon, Whatcom County, Skagit County, Seattle, King County, and greater western Washington. Call our Coupeville office to schedule an appointment by at 360-474-3994 or contact us online.