Forensic Toxicology ? Alcohol and Drugs

• Author: James Wigmore and James Watterson
• Pages: 719-772

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A. OVERVIEW: FORENSIC ALCOHOL AND DRUG TOXICOLOGY1

Forensic toxicology is the science of drugs and poisons (i.e., toxins) and

their adverse ef‌fects on the human body as applied to the medicolegal

context. Forensic toxicology has been generally divided into two main sec-

tions—(1) alcohol, and (2) other drugs—and, as such, this chapter has

been divided between the two to explore the various aspects of alcohol

and drugs in criminal cases.

Forensic alcohol toxicology focuses solely on the adverse ef‌fects of

ethyl alcohol in the human body and is one of the oldest of the forensic

sciences. The discipline’s long history is shown in Table 20.1.2

* Forensic Alcohol Toxicology.

** Forensic Drug Toxicology.

1 This overview section was written collaboratively by James Wigmore and James

Watterson.

2 A.W. Jones, “Measuring Alcohol in Blood and Breath for Forensic Purposes—A His-

torical Review” (1996) 8 Forensic Science Review 13; D.M. Lucas, “Alcohol and Driving:

The Development of Law Enforcement Countermeasures in Canada” (2009) 42 Can-

adian Society of Forensic Science Journal 237.

CHAPTER 20

Forensic Toxicology — Alcohol

and Drugs

James Wigmore* and James Watterson**

LEgAL ConTExT: CAiTLin PAkosH AnD sARAH HARLAnD-LogAn

720 6 James Wigmore and James Watterson

 20.1. Key Historical Developments in Forensic Alcohol Toxicology

Year Development

1803 Henry’s Law is published. This law determines a f‌ixed ratio between a volatile in air

and a liquid. It is the basis of breath alcohol testing.

1867 Breath alcohol concentrations are f‌irst determined in England by F.E. Anstie, who

uses an acid dichromate solution. This is the method of detection used by the

Breathalyzer when it is f‌irst developed in 1954.

1914 E.M.P. Widmark develops a method for analyzing blood and urine alcohol by using

an acid dichromate solution for medicolegal cases in Sweden.

1927 E. Bogen f‌irst describes the use of breath alcohol testing for medicolegal cases in

the United States.

1954 R.F. Borkenstein at Indiana University develops the Breathalyzer, the most success-

ful and widely used breath alcohol testing instrument for police enforcement of

drinking and driving laws. Approximately 30,000 Breathalyzers are manufactured

worldwide until production ceases in 1997.

1956 The Breathalyzer is f‌irst used in Canada by H.W. Smith of the Centre of Forensic

Sciences in Toronto. The Breathalyzer is used in Canada until 2010 but is then

replaced by the Intoxilyzer, which is introduced in 1994.

1958 First use of Gas Chromatography for alcohol analysis in a forensic laboratory in

Canada at the Centre of Forensic Sciences in Toronto.

1967 The Alcohol Test Committee of the Canadian Society of Forensic Science is

formed “to study scientif‌ic, technical and law enforcement aspects of breath tests

for alcohol.”*

1969 Mandatory breath alcohol testing and “over 80” laws are f‌irst enacted in Canada.

1976 Mandatory roadside alcohol screening is introduced in Canada.

1994 J.G. Wigmore and J. Patrick f‌irst introduce the Intoxilyzer in Toronto to replace

the Breathalyzer. The Intoxilyzer employs infrared (IR) light to detect alcohol and

becomes the most common method for evidential breath alcohol testing by the

police in Canada.

* Canadian Society of Forensic Science, “Canadian Society of Forensic Science Alcohol Test Commit-

tee Recommended Best Practices for a Breath Alcohol Testing Program” (4 May 2014) at 1, online:

www.csfs.ca/uploads/3/2/2/1/3221058/2014_05_04_best_practices.pdf.

Forensic drug toxicology also has a lengthy history but focuses on a

variety of drugs and toxins, unlike forensic alcohol toxicology. This disci-

pline may be subdivided into three general areas: post-mortem toxicology,

human performance toxicology, and forensic drug testing.

Post-mortem toxicology involves the analysis of biological samples

derived from a decedent as part of a death investigation and the in-

terpretation of those analyses to determine whether drugs (includ-

ing alcohol) were causative of, or contributive to, death. Various

sample types may be analyzed, but blood, urine, and visceral tissues

Forensic Toxicology — Alcohol and Drugs 6 721

are the most common samples analyzed in post-mortem toxicology.

The goal of post-mortem toxicology is to use these analyses of bio-

logical samples to assess the degree of toxicity experienced by the

decedent.

Human performance toxicology involves the analysis of biological

samples derived from a subject as part of an investigation that has

the goal of determining whether the subject was impaired with re-

spect to the performance of a specif‌ic task. Very often, the task in

question is the operation of a motor vehicle, but the approach may

be extended to cases involving allegations of sexual assault where

there is evidence of voluntary or involuntary exposure to drugs and

wherein the complainant’s state of intoxication is relevant to the

case. Analysis of biological samples (typically urine) for perform-

ance-enhancing drugs also falls under the category of human per-

formance toxicology.

Forensic drug testing, in this context, refers to any toxicological an-

alysis wherein the goal is simply to assess whether the subject has

been exposed to drugs in the recent past. The sample types ana-

lyzed in these scenarios are often urine or hair, since those sample

types are associated with longer time windows of detection.

The case types encountered in forensic toxicology can vary consider-

ably. In post-mortem toxicology, the death investigation (which requires

forensic toxicology analyses) may include criminal homicide investiga-

tions. A very large portion of forensic toxicology casework is related to al-

legations of impaired driving, where the vast majority of such cases focus

on the role of alcohol as the impairing substance. In cases where the role

of alcohol can be ruled out, further analysis of biological samples for the

presence of drugs may be undertaken where the attending of‌f‌icer can es-

tablish grounds. In such cases, the subject may undertake standardized

f‌ield sobriety tests and subsequent examination by a drug recognition ex-

pert (DRE) for the collection of physiological measurements (e.g., pupil

size, reactivity to light, pulse, blood pressure). Where these examinations

provide indications of impairment, the Canadian Criminal Code provides

for of‌f‌icers to make a demand for biological samples (i.e., blood, urine,

or oral f‌luid). Toxicological analysis is then used to verify drug exposure,

and is interpreted in terms of whether the analytical results are consistent

with the DRE observations. Other criminal case types encountered include

sexual assault and administration of a noxious substance.