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Monthly Bulletin of Case Reports & New Toxicological Studies
28 years of noteworthy & celebrated forensic toxicology cases
William R. Sawyer, Ph.D., Toxicologist
  • Diplomate, American Board of Forensic Medicine
  • Diplomate, American Board of Forensic Examiners
About Us
TCAS, LLC, provides a wide range of professional services including review of chemical, alcohol, pharmaceutical or radiological exposures within civil and criminal litigation matters.  Dr.  Sawyer has considerable expertise in matters pertaining to alcohol intoxication assessment,  intentional poisoning homicides, occupational and community exposures to carcinogens, medical malpractice involving pharmaceuticals, pyrolysis products, heavy metals, organic chemicals, dioxins and drugs of abuse. Forensic toxicology and toxic exposure investigations include analytical protocol and referral of autopsy material for analyses.  Environmental and occupational health risk assessments include site-specific assessments, dose measurement and causation determination. Final work products include scientific method references, method validation, forensic chain-of-custody and written reports.  Reports and expert witness testimony have been provided  to multiple clients in over 30 states.
Please Note
We routinely work throughout North America from the Virgin Islands and the Bahamas to Alaska in addition to providing expert international testimony as far away as Hong Kong.  We have offices in the states of New York and Florida.
Contact Us
Toxicology Consultants & Assessment Specialists, LLC

6450 Pine Avenue
Sanibel, Florida 33957

29 Fennell Street
Skaneateles, New York 13152

FL: 239-472-2436
NY: 315-685-2345

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American Board of
Forensic Medicine

Issue No. 11
Welcome to the latest edition in our series of short summaries of forensic toxicology matters taken from actual TCAS, LLC, cases over the past 28 years. Each case summary is factual, although identifying case information has been removed unless revealed through jury verdict reports. While interesting to read, the purpose of these case summaries is to show how the application of toxicological principles can be used in forensic matters. On occasion, we will also be releasing summaries on new toxicological studies and regulations.

TCAS, LLC, sends this newsletter to our past and present clients with the hope that it is of value in their professional endeavors.

In the event you have an interesting case you would like to discuss, please feel free to call or email us for a prompt, confidential teleconference.

Dr. Sawyer 
Acute Marijuana Intoxication Contributes to Fatal Motorcycle Accident
This case study illustrates how circumstantial evidence can be misinterpreted and how drug-impaired judgment and behavior can be regarded as evidential in a toxicological causation assessment.

A motorcyclist was fatally injured when he collided with a city bus in a business district. The weather was clear and fair, the posted speed limit was 30 mph and traffic was reported to be light at the time of the collision. The bus (which was empty at the time and traveling at approximately 25 mph) was making a left turn into a bus garage terminal when the collision occurred. The driver died on impact.

A motorcyclist was fatally injured when he collided with a city bus in a business district.

Witnesses stated that the motorcyclist attempted to decelerate as the bus turned, but the back tire of the motorcycle rose into the air, causing the bike to flip over and collide with the bus. A multi-camera DOT video recording from the bus revealed no apparent events or unusual distractions. Witnesses reported that the motorcycle was traveling at a high rate of speed.
The motorcyclist's family alleged negligence on the part of the bus driver and filed a lawsuit, demanding not less than $3.8 million dollars. Defense attorneys representing the bus company retained Dr. Sawyer to conduct an independent toxicological assessment.

Assessment Strategy
Dr. Sawyer compiled and reviewed the case records including accident scene photos, multiple video recordings from the bus cameras, police reports and diagrams, witness statements, climate data, the medical examiner's autopsy report, the forensic toxicology report and the motorcyclist's personal medical records. Upon closer scrutiny, several significant factors relevant to the case came to light:
  • Two weeks prior to the accident, the young motorcyclist had visited his doctor complaining of dizziness. At that time, he revealed that he had smoked marijuana earlier in the day. Although there was a history of occasional alcohol consumption noted in his medical report, marijuana consumption appeared to be a more regular activity.
  • Although several witnesses reported seeing the motorcycle traveling at high speed just prior to the accident, this could not be immediately corroborated. However, upon closer examination of the video, it was determined that the motorcycle was approximately 300 feet away when the bus began to turn. Had the motorcycle been traveling at 30 mph, it would have taken 7 seconds to cover that distance; however, it took less than 3 seconds to reach the turning bus.
  • The soundtrack from the video recording revealed that the motorcyclist had downshifted 2 seconds prior to impact, rather than initially applying brakes to avoid the collision. This decision was remarkable given the high rate of speed at which the motorcycle was traveling.
  • The autopsy revealed no alcohol in the motorcyclist's blood. However, active cannabinoid and its metabolites (the constituent of marijuana) were detected in the blood analyses.
Based on these findings, Dr. Sawyer elected to conduct a pharmacokinetic assessment to determine when the marijuana was smoked and if the reported cannabinoid blood levels were consistent with impairment sufficient to degrade the motorcyclist's reaction time and judgment at the time of the accident. In Toxicology, the metabolite ratios of THC (Tetrahydrocannabinol, the psychoactive ingredient in marijuana) can be measured for this purpose. Dr. Sawyer relied on controlled studies which documented the ratios of active THC to the carboxy-THC metabolite to determine the time elapsed since dosing. This, in turn, would establish when it was administered and whether the blood level was sufficient to contribute to the accident.

Pharmacokinetic Methodology

The two primary metabolites at issue are the 11-hydroxy (active) and delta-9-carboxy (inactive) THC metabolites. Initially after smoking, active THC blood levels rapidly rise with peak levels occurring at approximately five minutes and then decreasing. Simultaneously, the delta-9-carboxy THC metabolite slowly increases (accumulates) as THC is transformed into the inactive metabolite. After 10 to 15 minutes, levels of these two metabolites are approximately equal.

The total and relative amounts of these components were significant in this case. Since the motorcyclist's postmortem blood analyses revealed slightly more active THC vs. carboxy-THC levels (2.8 and 2.7 ng/ml, respectively), Dr. Sawyer was able to offer a supported opinion that the motorcyclist smoked marijuana approximately 10 to 15 minutes before his death.

Additionally, Dr. Sawyer cited a recent peer-reviewed study by Ramaekers, et. al.1,2 which demonstrated that the blood levels of 11-hydroxy THC and delta-9-carboxy-THC (two marijuana metabolites) are generally equal at approximately 10 to 15 minutes after smoking. He further cited studies which documented adverse motor control and cognitive effects using up to 20 subjects in a controlled setting. Primary findings included:
  • Peak impairment occurred within the first hour after smoking.
  • Impairment was significant at THC levels between 2 and 5 ng/ml. For reference, this level is similar to a blood alcohol concentration (BAC) of 0.08%.
  • Cognitive function deficits (based on the "Tower of London" test) and impaired reaction time.
  • Impact at low levels was relevant to the safe operation of a motor vehicle.
Courtroom Showdown

Dr. Sawyer assembled a detailed report and presented his testimony to the court. His findings offered objective reasoning (supported by peer-reviewed studies and substantial toxicological literature) that the motorcyclist displayed impaired judgment with respect to operating his motorcycle at high speed down a city street. The reaction of downshifting rather than braking just prior to the crash strongly suggested an impaired response. Dr. Sawyer further noted that event reconstruction experts estimated a speed in excess of 100 mph before impact. All of these factors were consistent with THC impairment based on the blood analyses. As a consequence, the motorcyclist presented an unreasonable scenario that the bus driver could not have avoided. 

Plaintiffs' counsel vehemently denied Dr. Sawyer's findings and filed strongly worded pre-trial motions to exclude his testimony, accusing Dr. Sawyer of presenting testimony which "...lacks foundation, is speculative, is based on hearsay and invades the province of the jury." 

In his rebuttal, Dr. Sawyer addressed these attacks point for point. In particular, he noted that plaintiffs' assertion that the level of THC was insufficient to induce impairment was incorrect, citing numerous sources from NTSB (National Transportation Safety Board)3,4 and others demonstrating that the THC dose was more than sufficient to impair judgment, reaction time and corrective actions. 

Plaintiffs also asserted that a third THC metabolite (11-hydroxy delta-9 THC) should have been present at one-fifth the level of delta-9 carboxy THC, but was not detected in the blood analyses. Dr. Sawyer pointed out that the amount in the motorcyclist's blood was below the laboratory level of detection (LOD). Thus, it did not mean that the chemical was absent, but that it was below the minimum level that the laboratory instrument could detect. Dr. Sawyer further noted that if the motorcyclist had smoked the cited quantity of marijuana 10 to 15 minutes before the accident as outlined, the THC blood levels would have been precisely as measured in the autopsy report.


Expert testimony based on scientific principles or procedures is admissible in court, but only after a principle or procedure has gained general acceptance in its specified field. All of the sources cited by Dr. Sawyer in his toxicological assessment were from generally-recognized, peer-reviewed and governmental sources accepted by the relevant toxicological community.

Dr. Sawyer's assessment left very little "wiggle room." The judge dismissed plaintiffs' Motion to Exclude without even a written summation. It took the jury a mere 30 minutes to render a defense verdict of "Not Liable."


At the present time, some states have legalized marijuana and others are leaning in that direction. As this cultural process unfolds, it will become increasingly important for both scientific and legal professionals to offer causative determinations that are both scientifically credible and socially responsible. However, distinguishing between fact and opinion is not as easy as it may appear. To that end, it is helpful to remember that the "weighing instrument" for "weighing evidence" is always human cognition.

In this case, objective blood levels and metabolite ratios provided the court with its most compelling scientific evidence. Dr. Sawyer's attorney client kindly characterized his courtroom testimony as "...truly impressive and the highlight of the case."

A Message from Dr. William R. Sawyer
Chief Toxicologist, TCAS, LLC

"Comparing objective blood levels to generally-accepted, peer-reviewed studies can provide a jury with compelling information upon which to arrive at a verdict, especially when the case facts are consistent with the blood evidence."

Notes and References
Ramaekers, et. al., "Dose related risk of motor vehicle crashes after cannabis use," 2004 Feb 7;73(2):109-19
National Highway Traffic Safety Administration, "Marijuana & Alcohol Combined Increase Impairment," Number 201, June 1999
Christopher Hart, National Transportation Safety Board, "Planes, Trains and Automobiles: Operating While Stoned," Washington, DC July 31, 2014

(Disclaimer: Toxicology case studies are impartial and objective summaries of toxicological matters in which TCAS, LLC, was retained for the purpose of assessing health-based factors which, in some cases, led to a determination of causation. No names or identifying information have been provided due to privacy and legal considerations. In the above matter, Dr. Sawyer was retained by the defendant.)

Meet the Firm
Dr. William R. Sawyer is a professional toxicologist with a doctorate in toxicology from Indiana University School of Medicine. He is a diplomate of the American Board of Forensic Medicine and has more than 28 years of extensive experience in public health and forensic toxicology with specialized expertise in causation analyses (for plaintiff and defense) involving alcohol, drugs-of-abuse, pharmaceuticals, herbal products, dioxins, solvents, heavy metals, crude oil, radionuclides/NORM and other substances. Dr. Sawyer has testified at trial and/or deposition in more than 30 states including NY, MA, CT, PA, RI, NH, DE, NJ, WV, VA, NC, SC, GA, FL, AL, MS, LA, AR, MO, KY, IN, IL, WI, MI, OH, MN, MT, WA, CA, TX and OK.   Additionally, he has provided international expert testimony as far away as Hong Kong. As a skilled scientist and communicator in the area of toxic tort, Dr. Sawyer provides services to governmental agencies, corporations and select plaintiffs or defendants.  Dr. Sawyer currently serves as the Chief Toxicologist forTCAS, LLC,  and also has been an Assistant Professor (adjunct) for 23 years with the Department of Medicine, Upstate Medical University, Syracuse, New York. Dr. Sawyer has approximately 14 years experience as a licensed clinical and environmental laboratory director in several states. Dr. Sawyer is a distance swimmer for the Gulf Coast Swim Team and recently completed the "Swim Around Key West" race in just under six hours. He is also a triathlete with the distinction of being a four-time Ironman. He loves to fish and SCUBA dive in northern New York State and the Gulf of Mexico.

Funmi Afelumo began working with Dr. Sawyer in March 2015. He recently graduated from the State University of New York - College of Environmental Sciences and Forestry (SUNY-ESF) with his master's degree which focused on Plant Science and Biotechnology.  His graduate research project was in the field of phytoremediation - specifically increasing plant tolerance to toxic heavy metal exposure. He has been performing research in the field of phytoremediation and environmental health and safety since 2010. He has presented his research at several conferences including those for environmental health and biotechnology. Funmi particularly enjoys that at TCAS he gets to use scientific knowledge and reasoning to help solve problems and make society better.  When not reading scientific journals and other literature, Funmi enjoys hiking through New York's beautiful parks and volunteering.

Jennifer Clark  (Jen) began working with Dr. Sawyer in 2007 after spending the previous 18 years as a full-time mom. With a background as a legal assistant prior to the birth of her two daughters, Jen spends a considerable amount of her time performing research for active TCAS cases. Not only does she have a special ability to ferret out information, she also has excellent grammatical skills which she applies to communications and report preparation. Jen loves a challenge and the fact that no two days at TCAS are the same! When not being an honorary toxicology investigator, Jen enjoys gardening, camping, reading and solving jigsaw puzzles. She is also a huge fan of the Adirondack Mountains of upstate New York and spends several weeks each summer exploring the woods and lakes with her husband, Jim, and golden retriever, Gracie.

Bonnie Serling, the newest  member of TCAS, was hired in September of 2015 as an administrative assistant.  She studied at Clarkson University, where she earned her BS in chemical engineering.  Bonnie continued her education at University of Rochester, where she performed graduate research in microcirculatory hemodynamics. These studies resulted in her earning a MS, also in chemical engineering. 
Bonnie enjoys reading, solving word and number puzzles, and tackling home improvement projects, especially painting.   She owns and operates a photography company, specializing in preschool and elementary school children.  She and her husband have three children, aged 21, 18, and 15. As an enthusiast of problem-solving, Bonnie loves being a part of providing answers to the challenging cases here at TCAS.   

Carol Sawyer serves as bookkeeper for TCAS, LLC. By training, she is a dental hygienist and graduate from Indiana University School of Dentistry. She also has prior training and work experience in an accounting firm as a file room clerk and has managed company records since its inception in 1989. Carol enjoys preparing specialty foods, volunteering in her church and community, visiting barrier island beaches, reading and just being outdoors.

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This newsletter archive contains informational and instructional publications devoted to toxicology, compiled as a useful educational resource. Footnotes, image sources and references are cited where appropriate. Copyrighted material may only be reproduced and/or distributed with prior permission from TCAS, LLC.