State v. Beltran-Chavez, 400 P.3d 927

Background

Defendant struck another car, left the scene, was later contacted by Deputy Dueñas who smelled alcohol and observed signs of intoxication; Dueñas administered HGN, walk‑and‑turn (WAT), and one‑leg‑stand (OLS) field sobriety tests (FSTs).
Dueñas testified defendant exhibited 4 of 8 WAT clues and 1 OLS clue and answered “Fail” when asked whether 4/8 on WAT was passing or failing; he also testified defendant was impaired. At the station two breath samples read .082 and .079; the reported test result was .07.
Defendant moved pretrial to exclude testimony that he “passed” or “failed” WAT/OLS, arguing those terms import a scientific scoring rubric developed by research and require a Brown/O’Key foundation; the trial court denied the motion.
At trial the state admitted Dueñas’s “pass/fail” testimony without laying a scientific foundation; defendant was convicted of DUII and failure to perform duties of a driver.
On appeal the court considered whether testimony that a subject “passed” or “failed” WAT/OLS is scientific evidence requiring a Brown/O’Key reliability foundation and whether any error was harmless.

Issues

Issue	Plaintiff's Argument (State)	Defendant's Argument	Held
Whether testimony that a driver “passed” or “failed” WAT/OLS is “scientific” expert evidence requiring a Brown/O’Key foundation	“Pass/fail” is ordinary shorthand for an officer’s opinion about impairment; WAT/OLS are based on common‑knowledge principles and need no special scientific foundation	“Pass/fail” denotes use of a standardized scoring rubric tied to empirical research; jury will treat it as scientific, so state must establish scientific reliability first	Testimony that a subject “passed” or “failed” those FSTs is scientific because it relies on an external, research‑derived scoring rubric and thus required a Brown/O’Key foundation; admission without that foundation was error
Whether the challenged admission was harmless error	The other evidence (breath samples, officer observations, expert retrograde extrapolation) supported conviction; any error was harmless	Erroneous admission of scientifically perceived evidence likely influenced jury given borderline BAC evidence and non‑overwhelming proof of impairment	Error was prejudicial, not harmless; DUII conviction reversed and remanded
Whether officer descriptive observations of FST performance are inadmissible	Officer may testify to observable clues and offer opinion on impairment based on training/experience	Same; state argued observations and opinions are non‑scientific and admissible without Brown/O’Key	Observations and training‑based opinions remain admissible; holding limited to the numeric “pass/fail” conclusion tied to a standardized scoring rubric
Whether to decide the claimed jury‑instruction error about breath test	(not reached on appeal because DUII reversed)	(not reached)	Court declined to address because remand might develop different record

Key Cases Cited

State v. Brown, 297 Or. 404 (admissibility framework and factors for scientific expert evidence)
State v. O'Key, 321 Or. 285 (gatekeeping: when testimony will be perceived as scientific and must be shown reliable)
State v. Marrington, 335 Or. 555 (behavioral‑science expert testimony can be perceived as scientific when grounded in studies/research)
State v. Rambo, 250 Or. App. 186 (distinguishing training/experience‑based opinions from scientific evidence)
State v. Mazzola, 356 Or. 804 (rationale for admitting FST performance as indicators of balance/divided attention)
State v. Whitmore, 257 Or. App. 664 (harmless‑error standard for erroneously admitted evidence)