Testimony dealt with harmful effects

Harold Kalant

After reading the article by Pearce Bannon on the marijuana trial in
London, Ontario ("Crown witness admits dangers exaggerated: Clip from
reefer Madness caps last day of testimony," May 16), I am writing to
correct a fundamental error in the reporting of my testimony.

I was not a witness for the prosecution in the sense of testifying in
support of the charges against the accused; rather, I was an expert witness
called by the Crown to summarize the current state of knowledge about the
medical effects of cannabis use, including both the harmful and the
medically useful effects. The role of the expert witness is to present that
knowledge as clearly and impartially as possible, and I would have given
exactly the same evidence if called by either side.

Therefore I did not "admit" or "acknowledge" that the dangers of cannabis
were exaggerated, because I was not there to defend everything that had
been said about them. I stated clearly that I did not agree with the
exaggerated claims, but made it equally clear that there is good evidence
of the production of various harmful effects in regular heavy users.

Contrary to the impression given by your report, the question of
exaggerated claims made up only a small and relatively unimportant part of
my testimony.

Most of my testimony dealt with such adverse effects as lung disease,
impairment of driving ability, effects on memory, problem solving, and
other psychological functions, effects on the children of mothers who
smoked cannabis during pregnancy (Dr. Peter Fried's study in Ottawa), and
the precipitation of relapse in patients with preexisting psychiatric
disorders.

I also spoke of the potential beneficial effects of new drugs derived
chemically from cannabinoids, that hold considerable promise for the
treatment of various medical problems.

However, I emphasized that medical use and nonmedical use are completely
separate issues, that should not be confused. Heroin is again legal in
Canada for the treatment of pain in terminally ill cancer patients, yet
nobody argues that therefore it should be freely available to everybody for
nonmedical use.

Similarly, any decision about the legalization or nonlegalization of
cannabis for nonmedical use will have to be a political decision based on
our society's collective values, traditions, attitudes and goals.

It is a completely separate matter from the role of the Food and Drug
Directorate in reviewing the medical evidence about the efficacy and safety
of cannabinoid drugs for use in treating disease.

Harold Kalant, MD, PhD

Professor Emeritus of Pharmacology, University of Toronto