State v. Hedgpeth, 452 P.3d 948

Background

Defendant was stopped for riding a motorcycle without a helmet, later arrested for DUII; a breath test administered 1 hour 55 minutes after the stop showed a BAC of .09 and defendant had consumed no alcohol in the interim.
The state prosecuted solely under the per se provision (ORS 813.010(1)(a))—that the driver had .08% or more at the time of driving—and the trial court excluded the defendant’s evidence about partition‑ratio variability.
The trial court (sitting as factfinder) convicted based only on the .09 test result; the Court of Appeals reversed, concluding common knowledge that BAC dissipates over time was insufficient to permit a non‑speculative inference that defendant’s BAC was ≥ .08 when driving.
The Oregon Supreme Court granted review to decide whether common knowledge about alcohol dissipation can bridge the temporal gap between a later BAC test and the defendant’s BAC while driving.
The Supreme Court affirmed the Court of Appeals: on this sparse record (no evidence of when/what defendant drank, no symptoms, no testimony about absorption/elimination), the generic proposition that BAC falls over time was inadequate to support a non‑speculative inference that defendant’s BAC was ≥ .08 when he drove.
Justice Balmer dissented (joined by Baldwin), arguing that the bench factfinder reasonably could infer guilt from the undisputed .09 result nearly two hours later and the absence of drinking in the interim; she warned the majority’s rule may force experts in most cases.

Issues

Issue	State's Argument	Hedgpeth's Argument	Held
Whether common knowledge that BAC dissipates permits a reasonable, non‑speculative inference that a .09 BAC measured ~2 hours after driving means BAC was ≥ .08 while driving	Common knowledge that alcohol dissipates over time allows a factfinder to infer the earlier BAC was at least .08 (no alcohol consumed in interim)	Common knowledge is too general; without evidence about absorption/elimination, timing of last drink, symptoms, or expert extrapolation, any inference is speculative	Held: Insufficient. Generic common knowledge is too general on this record; something more is required to connect a later BAC to BAC at time of driving
Standard for reviewing a motion for judgment of acquittal (MJOA): scope of "reasonable inference" vs speculation	The factfinder may draw reasonable inferences from circumstantial evidence; a conclusion need not follow with logical necessity	Defendant urged a stricter requirement (logical syllogism/necessity) to avoid speculation	Held: Court applies the usual MJOA standard—view evidence in the light most favorable to the state and accept reasonable inferences—but those inferences may not be mere speculation; logical necessity is not required, yet the inference must be factually grounded

Key Cases Cited

State v. Eumana‑Moranchel, 352 Or 1 (describing that a later chemical test never by itself "shows" BAC at time of driving and that "something more" is needed)
State v. Clark, 286 Or 33 (explaining per se BAC method and noting common‑knowledge signs of intoxication)
State v. O’Key, 321 Or 285 (holding per‑se proof must rest on chemical analysis and limiting reliance on non‑chemical tests)
State v. Daniels, 348 Or 513 (discussing impermissible speculation vs reasonable inference)
State v. Hall, 327 Or 568 (factfinder may choose among multiple reasonable inferences)
State v. Jesse, 360 Or 584 (distinguishing reasonable inferences from speculation)
Missouri v. McNeely, 569 U.S. 141 (explaining variability in elimination rates and factors affecting BAC dissipation)