EvidenceProf Blog

Editor: Colin Miller
Univ. of South Carolina School of Law

Wednesday, October 10, 2007

Eyes Wide Shut? Ill. Supreme Court Finds Frye Hearing Must Be Held Before HGN Test Results Are Admissible

The Horizontal Gaze Nystagmus (HGN) test has long been considered the most reliable way, short of blood or breath test, for the police to determine whether a person has been driving while under the influence.  We've all probably seen this method used in TV shows or movies:  the police officer places a pen about 10 inches in front of the driver's eyes, tells the driver to follow the pen with his eyes, and moves it from side to side.  The officer determines that the driver was under the unfluence if his pupils are unusually jerky.

In its recent opinion in People v. McKown, the Illinois Supreme Court called into question the admissibility of HGN test results.  At Joanne McKown's trial for driving under the influence, the state offered into evidence the results of her HGN test, and defense counsel claimed that the results should not be admissible until a Frye hearing was held to determine whether the HGN test is generally accepted as reliable in the scientific community (Illinois has not adopted the more recent Daubert test).

The trial court found the results admissible without a Frye hearing, and the appellate court affirmed; both took judicial notice of the general acceptance of the reliability of HGN test results based upon prior court decisions.  The Illinois Supreme Court, however, reversed, holding that a Frye hearing had to be held to determine whether there was general acceptance in the scientific community.

The Illinois Supreme Court found that up until 1992, most courts did indeed take judicial notice of the general acceptance of the reliability of HGN test results as an indicator of alcohol impairment.  It noted, however, that since cases in Pennsylvania and Kansas in 1992, which called into question the reliability of the test, a majority of courts have resolved the HGN issue only after at least a partial Frye hearing occured in their jurisdiction, with some finding the results admissible and others finding them to be inadmissible.  The Illinois Supreme Court thus remanded the case to the trial court.

I haven't done the research to determine the accuracy of the HGN test (according to one article, the National Highway Traffic Safety Administration says it is 77 percent accurate), so I'm not sure how accepted the test is in the scientific community.  I'm pretty sure, though, that most judges are similarly uncertain, and the precedent cited in McKown certainly appears divided.  Thus, it appears that the Illinois Supreme Court acted properly in finding that the trial court improperly took judicial notice, and it will be interesting and educational to see what the trial court determines after looking at the relevant research.



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The general acceptance test is hard to address for HGN because there is no profession where even a small fraction of members pays any attention to sobriety testing. For a recent review, see

Posted by: Steve Rubenzer | Nov 23, 2007 10:34:15 AM

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