Cannabis laws in the US in particular are ridiculous and disporportionate to the dangers of the drug. Its just helps the moral brigade sleep easier at night (after a few glasses of wine) knowing that "those darn druggie's" are being locked up. There are so many dangers related to alcohol with regards to alcohol related violence, drink drive incidents, not to mention long term health risks associated with alcohol, yet most people do not even realise how dangerous it is. How many incidents do you read in the papers about a group of individuals getting high on marijuana then causing violence? Cannabis relaxes you more than anything else, and i doubt even the more hardened thug would look for a fight after smoking weed..
I personally know of many individuals, and girls in particular who regularly go out and get ridiculously drunk (bout 3-4 times a week), yet berate any one who smokes weed, calling them stoners, drug addicts etc.
Public opinion on cannabis is misguided with relation to the relative harmful effects of the drug. Yes it does increase the risk of pyscosis, but as far as im aware it only heightens the chances of those who may already be suscebtable to this illness. This also only occurs after prolonged and regular use of cannabis.
I acknowledge that there are inherent risks of cannabis use and consequently there are prison sentences for those who sell or are caught in possession of an amount that would be intended to be sold (as far as I'm aware its an ounce), yet i do not feel that this is reflective upon the nature and the risks of the drug, especially as when compared with alcohol and its subsidiary effects.