State v. Hedgpeth, 415 P.3d 1080

Defendant was stopped for riding a motorcycle without a helmet, arrested for DUII, and given an Intoxilyzer breath test about 1 hour 45 minutes after the stop; result: .09% BAC.
Trooper testified defendant consumed no alcohol between the stop and the breath test.
State prosecuted solely under the per se provision of ORS 813.010(1)(a): BAC ≥ .08% at time of driving.
At the bench trial the court convicted after finding the .09% reading sufficient to infer BAC ≥ .08% when driving; defendant moved (in closing) for judgment of acquittal on sufficiency grounds.
On appeal the court reviewed whether the minimal evidence (a later .09% test + no additional drinking + common knowledge that alcohol dissipates) permitted a reasonable factfinder to infer the requisite BAC at the time of driving.
Court concluded common knowledge of dissipation alone is insufficient to infer a specific earlier BAC without additional evidence (e.g., expert retrograde extrapolation or other predicate facts), and reversed the conviction.

Issue	State's Argument	Defendant's Argument	Held
Sufficiency: Whether the .09% BAC measured 1 h 45 min after driving, plus no further drinking and common knowledge that alcohol dissipates, permits a reasonable factfinder to find BAC ≥ .08% at time of driving beyond a reasonable doubt	The later .09% reading and the undisputed absence of additional drinking allow a factfinder to infer the earlier BAC was at least as high (courts may rely on common knowledge of dissipation)	It is speculative to infer a specific earlier BAC from a delayed test without additional evidence on absorption/elimination rates; state failed to prove the per se element beyond a reasonable doubt	Reversed: Common knowledge that alcohol dissipates is not enough, by itself, to permit a reasonable inference that defendant’s BAC was ≥ .08% at the time of driving; additional evidence (expert retrograde extrapolation or predicate facts) is required
Evidentiary exclusion: Whether the trial court erred excluding evidence about breath-to-blood conversion ratios (defendant’s first assignment)	State did not oppose exclusion as dispositive here	Defendant argued conversion-ratio evidence was admissible to challenge the calculated BAC	Not reached: appellate reversal on sufficiency made resolution unnecessary

State v. Eumana-Moranchel, 352 Or. 1 (Or. 2012) (discusses admissibility of expert retrograde extrapolation and notes dictum that a later high breath/blood test may permit an inference of an earlier high BAC)
State v. Parker, 317 Or. 225 (Or. 1993) (dicta recognizing common-knowledge dissipation of alcohol; used to discuss when additional evidence is necessary)
State v. Conway, 75 Or. App. 430 (Or. Ct. App. 1985) (holding jury may draw inference from a post-arrest high BAC together with no drinking in between, based on common knowledge that alcohol dissipates)
State v. Bivins, 191 Or. App. 460 (Or. Ct. App. 2004) (explains difference between reasonable inference and speculation; factfinder may draw reasonable inferences from circumstantial evidence)
State v. Miller, 289 Or. App. 353 (Or. Ct. App. 2017) (reversing where the jury’s factfinding relied on speculation rather than a logically probable inference)
State v. Cunningham, 320 Or. 47 (Or. 1994) (sets standard for sufficiency review: view evidence in light most favorable to state and accept reasonable inferences)