State Ex Rel. Montgomery v. Miller
234 Ariz. 289
| Ariz. Ct. App. | 2014Background
- The State seeks special action relief from the trial court’s order precluding the State’s retrograde extrapolation expert testimony about Defendant’s BAC within two hours of driving.
- Defendant was stopped at 2:20 a.m.; blood was drawn at 6:15 a.m.; the BAC result was .127.
- Defendant was indicted on two counts of aggravated DUI; count Two requires BAC above .08 within two hours of driving.
- The State’s only proof to meet the two-hour BAC requirement relied on retrograde extrapolation because the blood test occurred about four hours after driving.
- The trial court excluded Musselman’s retrograde extrapolation testimony as unreliable under Rule 702/Daubert, and the State sought appellate relief; this Court grants relief and holds the testimony admissible.
Issues
| Issue | Plaintiff's Argument | Defendant's Argument | Held |
|---|---|---|---|
| Admissibility of retrograde extrapolation under Rule 702 | Musselman’s method is valid; peak BAC assumed within two hours and supported by data | Assumptions about peak BAC and lack of eating/drinking history render analysis unreliable | Admissible under Rule 702; expert testimony permitted |
| Reliability of evaluating unknown variables (eating/drinking history) | Unknowns accounted for with conservative assumptions and range of BAC | Lack of specific eating/drinking history makes extrapolation speculative | Methodology reliably accounts for unknowns; admissible evidence |
| Persuasiveness of Armstrong as controlling authority | Armstrong not persuasive authority for Arizona Rule 702 reliability | Armstrong suggests unreliability when not tied to drinking history | Armstrong not persuasive; not controlling in Arizona context |
| Rule 403 balancing of probative value vs. prejudice | Retrograde extrapolation is probative and not unfairly prejudicial | Testimony could be unfairly prejudicial | Trial court erred in precluding testimony; no reversible prejudice |
| Daubert factors’ application to retrograde extrapolation | Daubert factors support testing, peer review, general acceptance, error rate, standards | Method not sufficiently tied to defendant’s personal consumption/history | Daubert factors satisfied; methodology reliable under Rule 702(d) |
Key Cases Cited
- State v. Claybrook, 193 Ariz. 588 (App. 1998) (retrograde extrapolation admissible when within two hours of driving)
- Ring v. Taylor, 141 Ariz. 56 (App. 1984) (retrograde extrapolation generally accepted in Arizona)
- Desmond v. State, 161 Ariz. 522 (1989) (pre-1990 statute required BAC at driving time; allowed extrapolation)
- Williams v. Thude, 180 Ariz. 531 (App. 1994) (statute amendments affecting BAC within two hours)
- Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993) (gatekeeping standard for reliability of expert testimony)
- Kumho Tire Co., Ltd. v. Carmichael, 526 U.S. 137 (1999) (Daubert gatekeeping applies to all expert testimony)
- Joiner v. General Electric Co., 522 U.S. 136 (1997) (focus on whether data support the expert’s conclusions)
- Bernstein v. State, 234 Ariz. 89 (App. 2014) (Arizona Rule 702 interpretation; gatekeeping guidance)
- State v. Armstrong, 277 P.3d 777 (Nev. 2011) (Nevada approach criticized as not controlling for Arizona)