PA Court Tosses DUI Conviction Due to Improper Police Testimony
Posted in DUI on July 2, 2025
Commonwealth v. Gause, 164 A.3d 532 (Pa. Super. 2017)
In a significant win for due process and evidentiary standards, the Pennsylvania Superior Court vacated a York County man’s DUI conviction after finding that police improperly offered “expert-like” testimony without the proper qualifications.
The Traffic Stop and DUI Charges
In Commonwealth v. Gause, police stopped Gause in the early morning hours after noticing that his vehicle’s taillights were not illuminated. During the traffic stop, the officer claimed to smell alcohol, and Gause admitted to drinking a single beer. Field sobriety tests were administered with mixed results, but notably, Gause did not show signs commonly associated with intoxication: no slurred speech, no fumbling of documents, and no issues with balance outside of the sobriety tests.
Despite the lack of significant indicators of impairment, Gause was arrested and charged with:
DUI – General Impairment (75 Pa.C.S. § 3802(a)(1))
DUI – Controlled Substance (75 Pa.C.S. § 3802(d)(2))
Driving without required rear lighting
The Flawed Testimony
The controversy arose during trial when the arresting officer testified that Gause’s “eyelid tremors” and “body tremors” were indicative of marijuana impairment. This contradicted the trial court’s pretrial ruling, which prohibited the officer from offering opinions on what those physical signs might mean.
Pennsylvania law clearly distinguishes between observations a layperson (like a police officer) can make, and scientific conclusions that require expert testimony. The Superior Court emphasized that connecting physical signs—especially subtle ones like eyelid tremors—to marijuana impairment requires specialized knowledge beyond the scope of typical police training.
Critically, there was no odor of marijuana, no physical evidence of drug use, and no admission from Gause that he had recently consumed marijuana.
Why the Conviction Was Overturned
The Superior Court ruled that allowing the officer to opine on marijuana impairment without being qualified as an expert was improper. The court found this error was not harmless because the testimony about tremors was central to the Commonwealth’s case. Without proper expert testimony, the evidence was insufficient to support the DUI – Controlled Substance conviction.
The court also found insufficient evidence to support the DUI – General Impairment charge. Despite the odor of alcohol, Gause’s demeanor, cooperation, and performance did not show substantial impairment. Furthermore, another officer admitted Gause was not “alcohol impaired” and that drug evaluation would not have been conducted if alcohol impairment had been present.
Key Takeaways for Pennsylvania Drivers
This case reinforces several critical points:
Police Cannot Substitute Themselves as Experts: Observations like bloodshot eyes or slurred speech are fair game for police testimony. But linking subtle or complex physical signs (like eye tremors) to drug impairment requires a qualified expert.
Insufficient Evidence Can Lead to Dismissal: DUI convictions require clear, admissible evidence that shows a driver was impaired to the point of being unsafe. Vague or improperly admitted evidence isn’t enough.
Defendants Have a Right to Challenge Improper Testimony: Pretrial rulings exist to prevent surprise or unfair testimony during trial. When those rulings are ignored, convictions can—and should—be overturned.
Why Legal Representation Matters
If you’ve been charged with DUI—whether alcohol, drugs, or both—it’s crucial to have an experienced defense attorney who understands the nuances of Pennsylvania DUI law. Improper police procedures and unreliable evidence can be challenged, and as this case shows, doing so can lead to a complete dismissal of charges.
Facing DUI Charges in Centre County or State College?
Contact an experienced criminal defense attorney today to protect your rights.
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