One of the most foolish and costly planks of the Conservatives' so-called 'get tough on crime' agenda is their plan to impose mandatory minimum terms of six months imprisonment on those who grow at least six marijuana plants.

It is instructive to consider the likely impacts of such a proposal. A 2005 study of seven years of marijuana cultivation arrests in British Columbia revealed that more than 80 per cent of growers did not have guns or traps at their sites, were not involved in organized crime, and were not involved in any theft of electricity. In other words, most marijuana cultivation takes place without imposing significant threats upon the surrounding community.

Further, and this apparently needs to be said repeatedly -- the consumption of cannabis is much less likely to lead to significant harm and premature death than the consumption of the perfectly legal and socially acceptable drugs -- alcohol and tobacco -- even when rates of use are taken into account.

There is a very real sense in which we -- or at least the Tories -- are operating without a shred of science on our side. Why are they doing this? The costs of jailing marijuana cultivators will soar into the billions of dollars within a few years -- and it will be the provinces, not the federal government, that will have to pay for the construction and operation of these new provincial facilities. Why have the provinces been so silent? Are they looking to create prison industries in rural areas of their jurisdictions, shoring up longstanding unemployment, and potentially converting these voters to their cause? Do they not care about the costs and the consequences of putting thousands of non-violent offenders in jail? Could this money not be better spent on health care, or other more useful collective endeavors?

In the land of the growers -- and the land of the users -- very little will change. The consumption of cannabis in Canada increased dramatically between 1965 and 1979, and then fell off quite dramatically until the early 1990s, rising again until a few years ago, but never quite hitting the rates of consumption of the late 1970s. These changing patterns of consumption appear, upon careful study and reflection, to have nothing to do with legislative or law enforcement initiatives.

For the growers, the six plant minimum will present some interesting choices. More will be at stake, with an increased possibility of imprisonment, and creative and sometimes desperate choices may well be made: increased theft of electricity, and increased arming of some of those involved in the industry, in recognition of the new risks. Police and prosecutors may also be reluctant to bring "mom and pop" marijuana cultivators to court, knowing that they will face at least six months in prison for their horticultural efforts.

There are other possibilities. The setting of the bar at six marijuana plants may produce innovation in the industry. Five marijuana plants will become a more popular norm for cultivation, with growers emulating the emerging European models of cannabis users' clubs, collectives growing only enough cannabis to meet the needs of their small groupings of adult users.

Whatever happens, we can be confident that neither the price nor the availability of cannabis will be significantly affected by the billions of dollars of our tax dollars that the Harper Conservatives are willing to spend to incarcerate non-violent cannabis entrepreneurs. During the past 50 years, marijuana's potency has increased and its price has dropped. Ironically, the price of daily use of cannabis is typically cheaper than the price of daily use of alcohol or tobacco, even though cannabis is illegal. I can already hear the Conservative response -- this is precisely why we must get tough.

But back here on planet earth, some of us pay attention to history. Getting tough on pot has already been tried -- in 1968 more than half of all those convicted of marijuana possession in Canada went to jail for their crime, but marijuana use only continued to increase, hitting its current peak in 1979.

And in the United States a host of luminaries, Republicans and Democrats alike (Pat Robertson and Newt Gingrich among them) are currently looking for ways out of the difficulties that their country created in the mid 1980s by endorsing mandatory minimum terms for drugs.

What will convince the Harper government to change its course? Perhaps we should argue that it is God's will; urgings that we base our drug policy on science and history have, after all, been met with a disturbing silence.