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Major Studies of Drugs and Drug Policy
Canadian Senate Special Committee on Illegal Drugs
Volume I - General Orientation

Chapter 9

Use of marijuana for therapeutic Purposes

 There has been renewed interest in the issue of the use of marijuana for therapeutic purposes in recent years, particularly in Canada. In the wake of an Ontario Court of Appeal ruling which found the provisions of the Controlled Drugs and Substances Act to be unconstitutional pertaining to the therapeutic use of marijuana, the federal Health Minister made new regulations in July 2001 that give people with specified medical problems access to marijuana under certain conditions. Later that same year, an international conference on medicinal cannabis held in The Hague, Netherlands, drew delegates from Canada and several other Western countries.[1][1] Earlier, in 1999, the National Institute of Medicine in the United States published an assessment of the science base of marijuana and medicine.[2][2]

However, the scientific community – the medical community in particular – is divided on the real therapeutic effectiveness of marijuana. Some are quick to say that opening the door to medical marijuana would be a step toward outright legalization of the substance. Witness the following two quotes, the first of which is from a former director of the National Institute on Drug Abuse (NIDA) in the United States:


It is primarily the political muscle of the marijuana legalization proponents that today creates the motivation to do additional research on marijuana smoke. […] There is one explanation for the strident insistence of marijuana legalization proponents that only smoked marijuana will do as ‘medicine’. They appear to be determined to have sick medical patients smoking marijuana in the public eye. They want that outcome because that act legitimizes the use of marijuana by changing the common public perception of marijuana from a harmful drug to a useful medicine. [3][3]


Although many who champion medical marijuana use do so on compassionate grounds, with the firm conviction that smoked marijuana provides benefits unavailable by other means, much support comes from those who advocate the liberalization of drug policy and the decriminalization of drug use. [4][4]

It is true, as Professor Mark Ware pointed out in his testimony before the Committee, that in the current legal and political context, it is difficult to conduct studies and, more importantly, do so without being influenced by the heated debate over marijuana.


Let us look at the effect that current drug policy has had on our understanding of cannabis. All our data on the health effects of cannabis have been collected under a paradigm of prohibition. This may seem self-evident but it constitutes an important source of bias. In examining the health effects of cannabis, an estimate of the use of cannabis in the healthy population is important. […] Surveys of illicit drug use are notorious for poor response rates. It hampers our ability to draw conclusions on what cannabis does, if we don’t really know who is doing it. It is important to estimate the size of the bias, and the effect it has had, and good research will always try to minimize it. However, in my experience of critically reviewing the literature on cannabis effects on health, examples exist where important estimates of risk are based on studies which have inappropriate control selection. […] The question therefore changes from ‘how has cannabis policy affected health?’ and becomes ‘has cannabis policy affected our understanding of the health effects of cannabis?’ [5][5]


It is also true that the issue of medicinal marijuana challenges us on the very concept of modern medicine and its links with the pharmaceuticals industry, since research on cannabinoids has already led to the development of synthetic THC compounds. Drug companies are known to have played a major role in international negotiations leading to the adoption of the first international conventions on the control of psychoactive substances.[6][6] Moreover, the marijuana plant itself, because it cannot be patented, is of no interest to major pharmaceutical research groups.

Beyond the scientific “proof” that marijuana is effective and the prospect of physicians prescribing marijuana with sufficient confidence, many people believe, based on personal experience, that marijuana has a direct impact in terms of improving their well-being with minimum adverse effects. That view is what led to the creation of “compassion clubs”, organizations that distribute marijuana to growing numbers of clients. One of the questions this raises is how much evidence is needed before people can be allowed to freely use marijuana to relieve a medical condition. Indeed, do we have to think of marijuana in strictly medical terms?

We saw in Chapter 7 that the long-term effects of using marijuana, even on a regular basis, are limited and that even the most serious effects, such as lung cancer, have yet to be clearly demonstrated. We also saw that the adverse effects of prolonged use on cognitive function are more prevalent in people who are already vulnerable because of their young age when they started using, for example, or their personal condition (for example, psychotic predispositions). We also saw that, even assuming some tolerance and a certain level of psychological dependency, those effects are minor, the signs of withdrawal minor, and treatment shorter and less often necessary than for other drugs. To a degree, it appears that the psychoactive properties of marijuana, which some see coupled with rejection of society, others with a weak personality and still others with immoral behaviour, make the substance suspect, whether in medical or non-medical applications.

In that sense, the issue of medical marijuana is not so much a question of legalization through the back door as it is a question of open examination of each person’s underlying conception of the “drug”. In a way, it is a prime opportunity to explore our preconceptions and prejudices. Stating, as we did in Chapters 6 and 7, that the psychological, physiological or social effects of marijuana use are by all indications relatively benign says nothing about the therapeutic benefits of the plant in the same way that medical uses of the poppy say nothing about the individual or social harm that can be caused by heroin. Dr. Kalant echoed this view:


The separation of the control methods between medical and non-medical use is generally clearly understood. Both heroin and cocaine have limited but recognized medical uses. […] Yet, nobody argues that, because these drugs have some limited medical use, that they should therefore be legalized for non-medical use. […] Cannabis is perhaps the one exception in which possible medical uses are often claimed by some proponents of legalization of cannabis as a justification for legalization for non-medical use. This to me seems quite irrational. There is no logical reason why having a medical use should be any argument at all, either for or against, availability for non-medical use. [7][7]


However, as Dr. Ware reiterated, “the safety of cannabis in humans has been extensively studied, thanks in part to the massive Western cohort of ‘healthy human volunteers’ of the last 40 years. Cannabis may have undergone the most extensive and unorthodox Phase I clinical trials of any drug in history.”[8][8] While it is true that research protocols to allow medical use of a substance are and must remain rigorous, there is no clear boundary between the two areas of research. This was illustrated to some extent in the review in Chapter 7 of studies on the effects and consequences of marijuana. Indeed, the opposite approach struck us as more common, where, based on the presumed harmful effects of marijuana on psychological and physical health, the therapeutic usefulness of marijuana becomes at least suspect. We take as an example the position of the Canadian Medical Association.

In his testimony before the Commission, current CMA president Dr. Henry Haddad said:


While our understanding of all the possible long-term health effects that prolong Canada's use is still evolving, what we do know is troubling. The health risks range from acute effects such as anxiety, dysphoria, or the feeling of being ill; cognitive impairment to the chronic effects such as bronchitis, emphysema and cancer. Canada's youth have also been subject to pulmonary damage comparable to that produced by tobacco use but the effects are much more acute and rapid. Evidence suggests that smoking two or three cannabis cigarettes a day has the same health effect as smoking 20 cigarettes a day. Therefore, the potential long-term health effects of cannabis use could be quite severe.


The CMA's concerns regarding the impact of cannabis are in part why we are opposed to the federal government's current medical marijuana access regulations. In our May 7, 2001, letter to the Minister of Health, the CMA noted ‘lack of credible information on the risks and benefits of medical marijuana.’

During discussions on the government's medical marijuana regulations, we highlighted the health concerns and research that indicates that “marijuana is an addictive substance that is known to have psychoactive effects and in its smoke form is particularly harmful to health.''

We have concluded that while benefits of medical marijuana are unknown, the health risks are real. Therefore, it would be inappropriate for physicians to prescribe marijuana to their patients, a position that was supported by the Canadian Medical Association.



The CMA is concerned that this debate concerning decriminalization and the medical marijuana issue has, to some extent, legitimized its use for recreational purposes. It is important that our message to you regarding decriminalization be clear and understood. Decriminalization must be tied to a national drug strategy that promotes awareness and prevention and provides for comprehensive treatment in addition to research and monitoring of the program.



The CMA believes that any changes regarding illegal drug policy should be gradual. Like any other public health issue, education and awareness of the potential harms associated with cannabis and other illegal drug use is critical to reducing drug usage. [9][9]


If we were to succeed in showing that the effects are not as bad as had been thought, would it change in any way the issues related to medical use of marijuana? The acute effects identified by the CMA are possible but relatively rare and often the product of personal predispositions, context or a particular crop of marijuana. In fact, the primary acute reactions, the reactions documented by most of the research, are pleasant and help the user relax. If we were to convince the medical association that marijuana is not particularly addictive and that even where it is, the effects are relatively benign, would that clear the way for medical use of marijuana? Aside from the fact that marijuana is only tenuously linked to “drug addiction”, there is by no means consensus in the scientific community on the very notion of drug addiction, viewed primarily as a disease.

The question lies elsewhere – in two places, in fact. First, knowledge of the potentially harmful effects of marijuana says nothing about the qualities of the plant as a medicine. To be sure, knowledge of the secondary effects of drugs, including their addictive potential, is essential to the pharmacopoeia. However, those substances must first be established as drugs, particularly in terms of effectiveness and reliability. Second, the whole issue is broached as if resistance to medical use of marijuana were based not so much on the absence of medical knowledge per se – which is the case to some extent, as we will see later in this chapter – as on the link between marijuana and drug addiction. From that perspective, the issue is quickly resolved: in keeping with the medical maxim “first do no harm”, a physician will not prescribe a treatment the effects of which could lead to an illness at least as serious as the illness being treated in the first place. If marijuana is listed as an illegal drug, banned in some contexts because of its harmful effects and capable of leading to drug addiction, what compelling arguments could be put forward to “save” medical marijuana?

But none of that should matter to physicians or scientists. It is not a question of defending general public policy on marijuana or even all illegal drugs. It is not a question of sending a symbolic message about “drugs”. It is not a question of being afraid that young people will use marijuana if it is approved as a medicine. The question – the only question – for physicians is whether, to what extent and in what circumstances, marijuana serves a therapeutic purpose. Physicians would have to determine whether people with certain diseases would benefit from marijuana use and weigh the side effects against the benefits. If they decide the patient should use marijuana, they then have to consider how he or she might get it. The issue of deciding whether cannabis has therapeutic benefits is obviously clouded by the current legal context on cannabis. This may be inevitable, but those who take public positions on cannabis for therapeutic purposes should say so.

The rest of this chapter is devoted to the history of the use of marijuana for therapeutic purposes and the status of contemporary knowledge of marijuana and synthetic cannabinoids. We then give a brief account of compassion clubs and other organizations that supply marijuana for therapeutic use, as well as various public policy regimes. We conclude with our views on medical use of marijuana. In a later chapter, we discuss which public policy regime would be most appropriate given the status of medical use of marijuana.




[1][1]  International Conference on Medicinal Cannabis, November 22-23, 2001, The Hague, Netherlands.

[2][2] Joy, J.E., S.J. Watson and J.A. Benson (1999) (eds.), Marijuana and Medicine: Assessing the Science Base. Washington, D.C.: National Academy Press.

[3][3]  DuPont, R.L. (1999), “Examining the Debate on the Use of Medical Marijuana”, Proceedings of the Association of American Physicians, Volume 111, No. 2, page 169.

[4][4]  Rosenthal, M.S., and H.D. Kleber (1999), “Making Sense of Medical Marijuana”, Proceedings of the Association of American Physicians, Volume 111, No. 2, page 159.

[5][5]  Dr. Mark Ware, Assistant Professor of Family Medicine and Anesthesia, McGill University, testimony before the Special Senate Committee on Illegal Drugs, Senate of Canada, May 31, 2002.

[6][6]  See in particular the study by W.B. McAllistair, Drug Diplomacy in the 20th Century. This point will be discussed later in chapter 19.

[7][7]  Dr. Harold Kalant, Professor Emeritus at the University of Toronto, testimony before the Special Senate Committee on Illegal Drugs, Senate of Canada, first session of the thirty-seventh Parliament, June 11, 2001, Issue 4, pages 70-71.

[8][8]  Dr. Mark Ware, op.cit.

[9][9]  Dr. Henry Haddad, President, Canadian Medical Association, testimony before the Special Senate Committee on Illegal Drugs, Senate of Canada, first session of the thirty-seventh Parliament, March 11, 2002, Issue 14, pages 52-53 and 54-55.

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