Supreme Court Rules on Trooper’s Testimony on HGN in DUI Jury Trial

When a police officer is deciding whether or not to arrest a driver for DUI, he usually asks the driver to perform field sobriety tests. These tests include an HGN (horizontal gaze nystagmus) test. This test measures shakiness in the eyes when one looks to the side, and police agencies believe the test indicates alcohol use. The Washington State Supreme Court ruled last week that there are limits to the test, and the police cannot base an opinion of intoxication solely on such a test.

The Spokane Court Case

A Mead, Washington man was arrested after a high speed crash for the charge of attempting to elude a police vehicle. The officer didn’t want the suspect to perform the standard walk-and-turn or the one-leg-stand test because he thought the driver may attempt to flee. The sole test that the officer asked to have performed was the HGN. The Spokane Trooper testified that he had “no doubt” that the driver was impaired. The appeals court overturned the conviction and ruled that the it was improper for the officer to give his opinion on the impairment because this was for the jury to decide, and also because the HGN test by itself is not scientifically reliable to support such an opinion. The Supreme Court affirmed this decision.

What This Means for DUI Suspects

If you are charged with DUI and you take the case to a jury trial this legal precedent provides some guidance to the court on what limits to place on tests like the HGN. The court made it clear that officers cannot testify in such a way as to give the test an “aura of scientific certainty.” The court explained that troopers should not be able to imply that the HGN can reveal that someone is intoxicated and “impaired” on alcohol when the HGN test “simply shows physical signs consistent with alcohol consumption.” A police officer can testify that “the test revealed signs consistent with alcohol consumption” and cannot imply that the HGN gives scientifically certain results.
See our prior post on refusing this test.