Cannabis will not become legal in the foreseeable future, not due to its supposed health risks but because of the clash it would cause between economic legal theory and our liberal democracy.
Economic Legal theory basically purports that if something is superior in its economic viability versus its other downsides, then give it the green light. This of course begs the question of why the hell haven't Government introduced a taxed cannabis to the market. It is completely economically sound, you sell something with a tax and this tax then covers any of the speculated health risks that could emerge, and the surplus goes towards reducing public debt. This beats the currently expensive uphill battle the police fight against the drug, hands down. I do not necessarily support the drug, this is merely a presentation of the unbiased truth.
The reason cannabis will not be legalised is due to the fact that the Government will clearly have to introduce legislation banning its growth in house hold situations if they wish to tax it. If there is an option of 'growing your own' versus buying the expensive alternative, the answer is clear. DIY.
Here is where the liberal democracy and economic clash comes in to play. The Government would effectively be saying go ahead, smoke this now legal drug, but let us take the benefits from your pocket. By legislating against its domestic growth the Government, our elected role model and moral founder, would be saying 'do as I say, but do not do as I do.'
This could be argued against from a precedent basis, if one were to bring up the fact that it is still legal to brew your own alcohol and grow your own tobacco, even though they are mass produced and taxed. This is true, insofar as the Government has not legislated against the domestic production of these drugs, but they sit smug on a couple of obvious points. Brewing your own alcohol is timely and generally tastes like shit. Growing you own tobacco is also timely and the end product is once again nothing like you find in the store.
Cannabis is a different story, the most intellectually lacking members of our society could grow it. And they do. The Government knows this.
The argument against cannabis has always followed a detrimental-to-health based approach. If the Government were to legalise it, the real truth would be revealed that it is based on economic gain. This would be detrimental to the facade of our Government, hence its introduction is highly unlikely.
If the Greens spent less time trying to win favour of both sides of the house, they will realise this.