Wisconsin narcotics expert witnesses analyze controlled-substance handling, prescribing, diversion, and toxicology across clinical and forensic settings. They often come from pharmacy, addiction medicine, pain management, emergency medicine, and crime laboratory backgrounds. Many have experience with UW Health and Froedtert systems and Wisconsin’s opioid response infrastructure. They evaluate drug identification, chain of custody, impairment, overdose causation, and compliance with state and federal controls.