In a decision that is certain to have significant ramifications for the DUI defense bar, the Pennsylvania Supreme Court recently affirmed without elaboration the Superior Court’s decision in Commonwealth v. Weaver, 76 A.3d 562, on the question of whether horizontal gaze nystagmus (HGN) tests “are [in]admissible at a suppression hearing for lack of probable cause to arrest for driving under the influence absent any admission of foundation evidence presented to show that the HGN test is generally accepted in the scientific community.” 2014 WL 6750608. In Weaver, the Superior Court held that “it is clear that the rules of evidence governing a trial are inapplicable to a determination of probable cause” and that the Commonwealth’s failure to establish the general scientific acceptance of HGN tests at the suppression hearing therefore had no effect on the proper finding of probable cause for the arrest.
In an in-depth amicus brief, the Pennsylvania Association for Drunk Driving Defense Attorneys argued that the Court was putting the cart before the horse in accepting the general scientific validity of HGN tests, and that, in any event, evidence from Weaver suggested that the test was not correctly performed in that case. PADDDA’s amicus brief in the case can be found here. While ultimately unsuccessful, PADDDA’s argument is worth a further look.
Briefly, HGN tests are based on the notion that consumption of certain substances increases the rapid involuntary oscillation of the eyeballs. HGN refers to the lateral “bouncing” or jerking of the eyes from side to side. Proponents of HGN tests for DUI prosecutions argue that “eyes don’t lie” and that a positive HGN test is indicative of ethanol, inhalants, or other drug use. Yet, courts in other jurisdictions have not been convinced and have questioned the HGN test’s reliability and accuracy. Peer-reviewed scientific studies suggest that HGN may be attributable to any number of other causes, including such every day circumstances such as the flu, glaucoma, over-caffeination, excessive exposure to nicotine, and even changes in atmospheric pressure.
Nevertheless, the Superior Court in Weaver remained convinced that any argument over the admissibility (the scientific-reliability factor) was a matter for the trial itself, and not for a hearing to determine probable cause. Citing the United States Supreme Court, the panel related the “differences in standards and latitude allowed in passing upon the distinct issues of probable cause and guilt,” allowing that the rules of trial evidence are inapplicable in determining probable cause.
The facts in Weaver may have not been the best vehicle for PADDA’s amicus argument about the reliability of HGN as scientific evidence, as the defendant in this case was driving erratically, appeared sluggish and slow to reply to commands, and consented to a search of his vehicle wherein controlled substances were discovered. While it is not clear that the Superior Court dove into the science behind HGN, as far as the Pennsylvania Supreme Court was willing to consider the question of lack of scientific foundation for the HGN at the suppression hearing, under the United States Supreme Court precedent, this was the correct outcome.
Still, the circumstances around HGN testing make it doubly important that an individual facing criminal prosecution find counsel that possesses a firm understanding of applicable DUI law. Contact a Fairlie & Lippy lawyer today for a free consultation about your case.