State v. Wilt, 109 A.3d 439

Defendant Maureen Wilt was arrested as an intoxicated passenger after being seen driving earlier the night of Dec. 26, 2011; she had consumed wine at dinner and later drank from a bottle of 100‑proof Southern Comfort after a fall and head injury.
Police stopped the car shortly after the post‑injury drinks; a state trooper administered three standardized field‑sobriety tests (HGN, walk‑and‑turn, one‑leg‑stand) and testified defendant failed all three and was intoxicated.
The trooper testified he observed all six HGN clues and estimated Wilt’s BAC as “over a .10”; he also admitted he did not follow the special HGN protocol for subjects with an obvious head wound.
A hospital blood sample taken later showed a BAC of .160; state and defense experts used relation‑back calculations to estimate Wilt’s BAC at the time she allegedly drove, with estimates dependent on how much Southern Comfort she drank after driving.
At trial the court allowed the trooper’s HGN testimony and his BAC estimate; on appeal Wilt argued (1) the trooper was unqualified to estimate BAC from the HGN and (2) the HGN testimony should have been excluded because the trooper failed to follow the head‑injury protocol.
The majority affirmed, concluding any error in admitting the trooper’s HGN testimony or BAC estimate was harmless because the blood‑sample BAC and expert relation‑back testimony provided the critical link to impairment at time of operation.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Admissibility of trooper’s quantitative BAC estimate based on HGN	State concedes trooper was wrong to quantify BAC from HGN but argues any objection was not preserved and error (if any) is harmless	Wilt argued the trooper was unqualified to estimate BAC from HGN and admission was erroneous	Court: Admission was error but harmless; conviction affirmed because blood BAC and expert relation‑back made trooper’s estimate cumulative
Admission of HGN results after trooper admitted not following head‑injury protocol	State argued trooper was qualified and any protocol lapse went to weight, not admissibility	Wilt argued protocol failure rendered HGN results unreliable and should be excluded	Court: Admission proper; cross‑examination exposed the protocol lapse to jury and any error was harmless given the blood and expert evidence

State v. Fuller, 168 Vt. 396, 721 A.2d 475 (trial court discretion on admissibility) (Vt. 1998)
State v. Brooks, 193 Vt. 461, 70 A.3d 1014 (harmless‑error standard) (Vt. 2013)
State v. Hunt, 150 Vt. 483, 555 A.2d 369 (error harmless where evidence cumulative) (Vt. 1988)
State v. Carter, 164 Vt. 545, 674 A.2d 1258 (harmless‑error burden and standard) (Vt. 1996)
Fahy v. Connecticut, 375 U.S. 85 (harmless‑error prejudice inquiry) (U.S. 1963)