Chemical Toxicology Expert Witness Rudolph Johnson

Rudolph Johnson, PhD, is a Chemical Toxicologist with over 20 years of experience in analytical chemistry and toxicological investigations. Dr. Johnson's past experience includes directing the (1) clinical toxicology network, LRN-C, at the Centers for Disease Control and Prevention and (2) the Military Exposures Research Program at the US Department of Veterans Affairs. Currently, he serves as the Director of the Wisconsin State Laboratory of Hygiene and has a faculty appointment at the University of Wisconsin-Madison School of Medicine and Public Health, Department of Pathology.

Dr. Johnson focuses on two specialty areas:

(A) Toxicology: He offers causation opinions connecting dose, analytical detection, and biomarker findings to determine whether and to what extent an individual was exposed to a chemical or toxin.  The chemical or toxin may be inhaled, ingested or injected. This includes drug and alcohol testing.

(B) Laboratory Testing: He critiques or defends laboratory testing methodology, chain-of-custody, and quality assurance practices. He is an expert at evaluating conflicting testing data between two labs.

Litigation Support - Dr. Johnson works with plaintiff and defense litigation attorneys on toxic tort, product liability, and environmental and occupational exposure cases requiring causation analysis. He supports criminal defense and plaintiffs reviewing drug exposures (opioids, fentanyl analogs, polypharmacy) and alcohol testing. This includes chain-of-custody, and quality practices. Conflicting or inconsistent laboratory data, especially between multiple laboratories, is a specialty area of Dr. Johnson because he previously directed multiple clinical toxicology labs.

Dr. Johnson detects, quantifies, and interprets chemical and toxic exposure in human clinical samples. He is skilled in translating investigative information into causation opinions, connecting dose, biomarker significance, and clinical outcome—for poisoning, occupational, environmental, and mass-casualty toxicology cases.

Areas of Expertise: