Commonwealth v. Griffith, 32 A.3d 1231

Griffith was charged with driving under the influence of a drug to a degree impairing safe driving under 75 Pa.C.S. § 3802(d)(2) after an incident on May 5, 2006.
Blood tests showed Diazepam (Valium) 95 ng/mL and Nordiazepam 220 ng/mL, with Soma (Carisoprodol) taken that morning; Soma itself was not detected in blood.
A bench trial occurred on March 7, 2007; eyewitness testimony of reckless driving and officer observations were admitted; blood test results and prescription bottles were stipulated.
The trial court convicted Griffith under § 3802(d)(2) and sentenced her to prison, fine, and costs.
Superior Court reversed the conviction on the basis that expert testimony was required to prove causation under § 3802(d)(2) when prescription medications are involved.
This Court reversed, holding expert testimony is not categorically required; whether expert evidence is necessary must be assessed case-by-case under the statute’s framework.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Is expert testimony required to prove causation under § 3802(d)(2) when prescription drugs are involved?	Commonwealth: no mandatory expert testimony; impairment can be proven by circumstantial evidence.	Griffith/defendant: expert testimony is required to prove causation.	No mandatory expert testimony; case-by-case assessment allowed.
Was the evidence sufficient to prove Griffith was under the influence to a degree impairing safe driving under § 3802(d)(2)?	Commonwealth: officer observations plus blood findings and drug use sufficient.	Griffith: evidence insufficient to prove causation without expert testimony.	Evidence sufficient; conviction upheld.

Commonwealth v. Williamson, 962 A.2d 1200 (Pa. Super. 2008) (drug-influenced driving not dependent on precise drug level in blood)
Commonwealth v. DiPanfilo, 993 A.2d 1262 (Pa. Super. 2010) (evidentiary sufficiency under § 3802(d)(2) based on totality of evidence)
Commonwealth v. Etchison, 916 A.2d 1169 (Pa. Super. 2007) (marijuana metabolites; exposure to expert testimony nuanced by fat-solubility of drug)
Commonwealth v. Segida, 604 Pa. 103, 985 A.2d 871 (Pa. 2009) (alcohol impairment framework general; not strictly required to prove alcohol level)
Commonwealth v. Kerry, 906 A.2d 1237 (Pa. Super. 2006) (focus on inability to drive safely rather than specific blood alcohol level)
Commonwealth v. Horn, 395 Pa. 585, 150 A.2d 872 (1959) (medical opinion admissible but not required to prove intoxication)
Kozak v. Struth, 515 Pa. 554, 531 A.2d 420 (1987) (expert testimony when issues exceed lay understanding)