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Supreme Court Sends DUI Case Back to Orange County Court

Posted by Richard Wagner | Aug 18, 2022 | 0 Comments

Police stopped William Leahy for driving 55 mph in a 25-mile-per-hour zone in Orange County, California.  According to the officer,

Leahy's face was flushed, his eyes were red and watery, his speech was slurred, his balance was unsteady, and he exuded the odor of alcohol.

HGN - Horizontal Gaze Nystagmus Test

“Leahy took the HGN test. “Nystagmus is an involuntary rapid movement of the eyeball, which may be horizontal, vertical, or rotary. 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.”

The officer believed Leahy failed the HGN test and arrested him. The intoxilyzer breath test result was.10 percent.

The Orange County DA charged Mr. Leahy with driving under the influence of alcohol VC 23152(a) and driving with a blood-alcohol concentration of 0.08 percent or higher VC 23152(b).

Leahy's DUI Defense Attorney filed a motion to exclude evidence of the HGN test result based on People v. Kelly (1976) 17 Cal.3d 24; Frye v. United States (D.C. Cir. 1923) 293 F. 1013, 1014.

The Kelly rule (formerly the Kelly-Frye rule) requires the party who seeks to introduce evidence that is based on a new or novel scientific technique to establish the reliability of that evidence before it is admitted. 

The Kelly rule has three elements:

  1. The test must be generally accepted in the relevant scientific community; general acceptance means “a consensus drawn from a typical cross-section of the relevant, qualified scientific community” 
  2. Testimony must be given by properly qualified experts, and
  3. Correct scientific procedures must have been applied in the case before the court. 

Lawyers file motions in limine, asking the judge to admit or exclude evidence before the evidence is presented to the jury. The hearing on the motion in limine is done outside the presence of the jury. The goal is to avoid unnecessary objections or disruptive hearings during the trial.

The Orange County trial judge denied the motion to exclude the HGN test result.

The judge reasoned:

the Kelly-Frye rule does not apply because the nature of the HGN test isn't a specific test for the determination of alcohol; it is only a symptom that the officer is testifying to … in the same manner as he might be testifying to a symptom of slurred speech or a person's face turning red, or … bloodshot eyes. It would be on that type of reasoning that it would be allowed in.

Defendant was convicted of driving under the influence of alcohol VC 23152(a) and driving with a blood-alcohol concentration of 0.08 percent or higher VC 23152(b). He appealed. 


The Court of Appeal reversed the Orange County trial judge and overturned defendant's convictions. The court of appeal relied on the analyses of People v. Williams (1992) 3 Cal.App.4th 1326, 1332-1335 and People v. Loomis (1984) 156 Cal.App.3d Supp. 1, 5-7 and concluded:

[i]t was error to admit HGN evidence as either lay or expert testimony without a Kelly-Frye foundation, i.e., proof of general acceptance of HGN in the scientific community.


Mr. Leahy found himself in the California Supreme Court. The Supreme Court concluded,

the Court of Appeal correctly decided that the HGN test was a ‘new scientific technique' within the scope of the Kelly formulation, and for that reason, proof was required of its general acceptance by the scientific community.

The Supreme Court disagreed with the Orange County DA's argument that HGN testing is neither “new” nor “scientific.”

As for whether HGN is scientific, the Court cited People v. Stoll (1989) 49 Cal.3d 1136, where the Court said by reason of the potential breadth of the term “scientific” in the Kelly/Frye doctrine, the courts often refer “to its narrow ‘common sense' purpose, i.e., to protect the jury from techniques which, though ‘new,' novel, or ‘ “experimental,” ‘ convey a ‘ “misleading aura of certainty.”

The Court found it “unmistakable that a jury could be unduly and unjustifiably impressed by the aura of certainty emanating from the officers' description of HGN tests.”

The Supreme Court affirmed the judgment of the Court of Appeal, reversing Mr. Leahy's conviction. The Supreme Court sent Mr. Leahy's case back to Orange County for a Kelly hearing. The judge was ordered to determine whether the HGN evidence would be admissible evidence at trial.

Depending on the outcome of the Kelly hearing, the judgment could be reinstated or a new trial could be ordered.

The citation for this opinion is People v. Leahy (1994) 8 Cal. 4th 587.

When taking into account Horizontal Gaze Nystagmus test evidence, the following taken from the leading Ophthalmology textbook is insightful:

“Unfortunately, the fact that alcohol can produce horizontal gaze-evoked nystagmus has led to a “roadside sobriety” test conducted by law­ enforcement officers. Nystagmus as an indica­tor of alcohol intoxication is fraught with extraor­dinary pitfalls: many normal individuals have physiologic end-point nystagmus; small doses of tranquilizers that wouldn't interfere with driving ability can produce nystagmus; nystagmus may be congenital or consequent to structural neurologic disease; and often a sophisticated neuro-ophthal­mologist or oculographer is required to determine whether nystagmus is pathologic. It seems unrea­sonable that such judgments should be the domain of cursorally trained law officers, no matter how intelligent, perceptive, and well-meaning they might be.” Duane's Clinical Ophthalmology, Volume 2, Revised Ed. 1994, Vol. II, Page 20.

If arrested for DUI, call DUI Lawyer Richard Wagner for a FREE Consultation – (714) 721-4423.

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