Cannabis Some Challenges with Determining Impairment - A Forensic - - PowerPoint PPT Presentation

• Dr. Michael R. Corbett

Ph.D., LL.M., F-ABFT, FCSFS Forensic Toxicologist, Chemical Review Services Inc. Adjunct Professor, Forensic Science University of Ontario Institute of Technology

Cannabis – Some Challenges with Determining Impairment - A Forensic Toxicologist’s Perspective.

Illuminating the Field – Forensic Toxicology

Illuminating the Field – Cannabis

Casarett & Doull’s Toxicology

Toxicology – Definition - Academic

 Toxicology has been defined as the study of the

adverse effects of xenobiotics …

 Toxicology, like medicine, is both a science and an

• art. The science of toxicology is defined as the
• bservational and data gathering phase, whereas the

art of toxicology consists of the utilization of the data to predict outcomes of exposure in human and animal populations.

Gallo, M.A. (2013). History and Scope of Toxicology. In C.D. Klaassen (ed.), Casarett & Doull’s Toxicology: The Basic Science of Poisons, 8th ed. Toronto: McGraw Hill. (p.3.)

Society of Toxicology

Toxicology – Definition - SOT

 The study of the adverse effects of chemical,

physical or biological agents on people, animals, and the environment.

SOT – Specialty Sections

 27 speciality sections

 One of them is entitled Ethical, Legal, and Social Issues

Society of Forensic Toxicologists - SOFT

Forensic Toxicology – Definition - SOFT

 Toxicology is the study of the adverse effects of

drugs and chemicals

• n

biological systems. Forensic toxicology deals with the application of toxicology to cases and issues where those adverse effects have administrative

• r

medicolegal consequences, and where the results are likely to be used in court. Forensic toxicology is a modern science, based on published and widely accepted scientific methods and practices, for both analysis of drugs in biological materials, and interpretation of those results.

http://www.soft-tox.org/files/SOFT_Brochure_(2013).pdf

Alcohol – A Drug with Distinction

American Board of Forensic Toxicology - ABFT

Forensic Toxicology – Definition - ABFT

 Forensic toxicology encompasses the measurement

• f alcohol, drugs and other toxic substances in

biological specimens and interpretation

• f

such results in a medicolegal context. (current)

 The study and practice of the application of

toxicology to the purposes of the law. (prior)

http://www.abft.org/

Toxicology – Specialized Science

 A specialized science of the adverse effects of

chemicals on biological subjects (eg. people).

 Ethanol  Drugs  Chemicals  Biotoxins  Above terms are not mutually exclusive

Forensic Toxicology - Specialties

 Postmortem  Human Performance  Employment / Applicant (eg. Insurance)  Athletic Competition  Equine  Environmental

 overlap with some other fields  Occupational Medicine  Medical Toxicology  Epidemiology

Drug Testing – Some Considerations

 Specimens  Application: Clinical or Forensic  Nature: Screening or Confirmation  Result: Qualitative or Quantitative  Use: Investigative Aid or Evidence

Routes of Flow of Chemicals in the Body

[Casarett & Doull’s Toxicology, p.154.]

Immunoassay (IA)

 Urine – Clin / For – Screening – Qualitative – Investigative Aid

Gas Chromatography with Mass Spectrometry (GC-MS)

 Urine – Forensic – Confirmation – Quantitative - Evidence

Challenges with Determining Impairment – Times

Challenge 1: Time of Specimen Collection

Marijuana and the Cannabinoids

PL Concentrations After Smoking Cannabis

Challenge 2 – Time of Use

I Don’t Know

Challenge 3: Relating Test Result to Time of Incident

Human Growth and Development

Cannabis – Selected Psychoactive Effects

THC – Individual Subject Effects - High

Host Factors - Drug Response

Illuminating – Cannabis – Wake n’ Bake

Challenge 4: Time of Retainer

Expert Evidence

CLE – Interaction with Experts

 The expert’s opinion must be and must be seen

to be detached and independent.

 Counsel must be fair in ensuring that the expert

has proper material to formulate an opinion.

[Lauwers J., “Comments on Expert Evidence”, in Expert Reports at 8. (Paper presented to the MLST, 23 January 2012)]

CLE – Experts & Documents

 Experts must ensure that they obtain all of the

necessary documents and review them with a critical eye, rather than simply accepting information from a litigant.

[Troy H. Lehman, in Expert Evidence in Personal Injury Cases at 23. (Paper presented to Osgoode Prof. Develop., 2 April 2012)]

Expert & Counsel – Attempting to Walk on Water

Finishing Time