Campbell v. People, 2019 CO 66

Officer stopped Randy Campbell for a defective headlamp, smelled alcohol, observed bloodshot eyes and slurred speech, and saw physical clumsiness (dropped wallet; trouble exiting truck).
Officer administered three standardized field sobriety tests (HGN, walk-and-turn, one-leg stand); Campbell failed all three. Officer was certified and testified about training and experience.
Officer testified in detail about HGN administration, described six HGN "clues," said he observed all six, and opined that Campbell's HGN performance was inconsistent with sobriety.
Defense argued the officer’s HGN opinion required expert qualification under CRE 702; trial court admitted the testimony as lay opinion under CRE 701 and overruled objections.
Jury convicted Campbell of DWAI, open container, and defective headlamp; conviction affirmed on appeal by district court which treated the HGN testimony as lay opinion.
Supreme Court granted certiorari to decide whether the officer’s HGN testimony was expert opinion requiring CRE 702 qualification and, if error, whether it was harmless.

Issue	Campbell's Argument	People’s Argument	Held
Whether officer’s HGN testimony was expert testimony requiring CRE 702 qualification	HGN opinions rest on specialized training/knowledge and thus must be offered by a qualified expert	HGN observations are within ordinary perception; officer's descriptions were lay-observable facts	Court held HGN testimony was expert under CRE 702 and trial court erred in admitting it as lay testimony
Whether the trial court abused discretion by admitting HGN lay testimony	Admission without expert qualification was an abuse of discretion	Admission was within trial court’s discretion as ordinary lay testimony	Court concluded trial court abused its discretion
Whether the error was reversible (harmless error analysis)	HGN testimony was key and difficult to rebut; error affected substantial rights	Other evidence of intoxication was overwhelming so any error was harmless	Error deemed harmless given strong independent evidence of impairment; conviction affirmed
Standard for distinguishing lay vs expert under CRE 701/702	(applies Venalonzo) basis-of-opinion test: if opinion requires specialized knowledge, it’s expert	Same standard; urged lay status here	Court applied Venalonzo and found testimony required specialized experience/training, so CRE 702 applied

Venalonzo v. People, 388 P.3d 868 (Colo. 2017) (distinguishes lay vs expert testimony by basis for opinion)
Romero v. People, 393 P.3d 973 (Colo. 2017) (abuse-of-discretion review for evidentiary rulings)
Hagos v. People, 288 P.3d 116 (Colo. 2012) (harmless-error standard for nonconstitutional trial errors)
People v. Ramos, 388 P.3d 888 (Colo. 2017) (officer testimony requiring specialized knowledge is expert testimony)
People v. Stewart, 55 P.3d 107 (Colo. 2002) (admission error harmless where evidence of guilt overwhelming)
Tevlin v. People, 715 P.2d 338 (Colo. 1986) (erroneous expert admission may be harmless when guilt is overwhelmingly supported)