Carolina Criminal Defense & DUI Lawyer UpdatesShould Eyelid Tremor Be Used to Prove Cannabis Impairment in North Carolina?
For years, the Drug Recognition Evaluator (DRE) protocol has relied on a structured set of physical observations to evaluate suspected drug impairment. Among these, the presence of eyelid tremor has been taught as a supposed sign of recent cannabis use. In practice, that means law enforcement officers conducting roadside evaluations or testifying in court may point to an eyelid tremor as evidence supporting probable cause or impairment. But as a recent study published in Clinical Toxicology makes clear, the scientific foundation for this assumption is, at best, unproven. At worst, it is affirmatively misleading.
In a 2024 peer-reviewed clinical research article by George Sam Wang and colleagues, the authors conducted a carefully controlled, blinded study to evaluate whether eyelid tremor could reliably and accurately be identified as a marker of recent cannabis use. The conclusion was clear. Eyelid tremor does not correlate with cannabis ingestion in a scientifically defensible way. Inter-rater reliability was poor to moderate. Specificity was dismal. And perhaps most importantly for DWI defense lawyers, the entire protocol used by officers to “spot” this supposed indicator would not come close to passing scientific muster in any peer-reviewed laboratory setting.
a range of charges depending on the circumstances. Two of the most serious offenses are Felony Death by Vehicle and Second-Degree Murder.
tests, and standardized field sobriety tests.
and medical conditions that could affect impairment assessments. This article examines the different types of experts used in North Carolina DWI cases, how courts determine whether their testimony is admissible under Rule 702, and what legal considerations apply when presenting expert evidence in court.
Department of Transportation – Division of Motor Vehicles (DMV) may move forward with revoking your license for failing to submit to breath and/or blood testing. 
technical procedures—such as chemical breath tests, blood alcohol analyses, and field sobriety testing—that lay jurors or even judges may not fully understand. An expert witness, properly qualified and admitted, can provide insight into such complex matters both for the prosecution and the defense.
blood testing in a DWI case. Law enforcement may suspect drug involvement, or the driver may be unable (or unwilling) to provide a valid breath sample on an approved device. DUI fatalities tend to involve blood testing, as it the more accurate method to confirm the different possible sources of impairment and the respective concentrations of each.
evaluations play an important role in the legal process and can positively impact the outcome of your case.
Amendment. 
Sixth Amendment is violated when a substitute analyst provides expert witness testimony about the results of forensic testing performed by a non-testifying analyst.