Margaret M Gedde, MD, PhD, DABPath

Fredericksburg, Virginia

General Specialty


Specialty Focus

Blood Cannabinoids
Cannabinoid Medicine
Cannabinoid Pharmacodynamics
Cannabinoid Pharmacokinetics
Forensic Toxicology
Marijuana DUI/DWI
Marijuana Impairment
THC Blood Testing
THC Drug Testing
THC Impairment

Primary Areas of Expertise

Medical Toxicology


Medical Marijuana

Dr. Gedde provides clinical expertise in medical use of cannabinoids through her cannabis-focused Colorado practice. She is known for a clinical focus in use of cannabinoids in pediatric epilepsy.

Dr. Gedde is knowledgeable about the environment around medical marijuana for physicians and has been qualified in civil and administrative courts as an expert witness regarding the practice of cannabis medicine.

In addition to the MD degree, Dr. Gedde holds a PhD in Chemistry and Board Certification in Clinical Pathology, the medical specialty that includes toxicology. As a medical toxicology expert witness, Dr. Gedde brings authoritative clarity to interpretation of blood cannabinoids in criminal and civil THC DUI/DWI cases.

Dr. Gedde’s background also includes post-doctoral research into the molecular biology of bacterial pathogenesis at the University of California at Berkeley and five years in the pharmaceutical industry as a clinical microbiology director and consultant. She has been in clinical practice continuously since 2003.

A prosecutor using a THC blood test to support THC DUI charges relies on assertion that a blood level indicates intoxication, or that a blood level predicts intoxication at an earlier time. The prosecutor can be expected to elicit testimony from a medical toxicology expert witness to support this.

Yet, published, authoritative academic and governmental sources show that THC blood levels do not reliably indicate intoxication, and that extrapolation from a cannabinoid blood level to earlier blood levels or intoxication also is not possible.

As an expert witness in criminal and civil THC DUI cases, Dr. Gedde provides objective, data-driven interpretation of cannabinoid blood levels based on recognized sources, in testimony and in written reports. She helps defense attorneys use medical pharmacology and toxicology findings to prepare to cross-examine witnesses who testify regarding interpretation of THC blood tests.



MD, Stanford University School of Medicine
PhD Biophysical Chemistry, Stanford University Department of Chemistry
BA Biochemistry, Barnard College, Columbia University
Residency in Clinical Pathology, University of Pennsylvania Medical Center, Department of Pathology and Laboratory Medicine

There are currently no reviews for this expert

Get In Touch With Margaret M Gedde, MD, PhD, DABPath


content seperator