Research summary
A systematic review encompassing 101 studies compared roadside screening methods with laboratory cannabinoid testing. Oral-fluid tests had promising performance for detecting THC, although sensitivity varied across devices. A chemical screening result identifies possible exposure or drug presence under defined testing conditions; it does not independently establish functional driving impairment. Confirmation, assay characteristics, matrix, and timing must be evaluated separately.
Forensic interpretation
This research describes specific experimental conditions. It does not establish an individual driver’s impairment or the cause of an observed clinical finding without case-specific information. Analytical methodology, timing, dose, route of administration, and plausible alternative explanations should be assessed before making a forensic inference.