Let me say one thing about cannabis from the outset: I believe it is a dangerous drug.
Let me say another thing: I don't believe that cannabis possession should be a criminal offence. I have a number of reasons for thinking this.
(1) There is a gross hypocrisy about our drug laws. Whereas alcohol abusers are encouraged to seek help, cannabis abusers are sent to jail. The level of punishment associated with criminal offending is far out of proportion to the perceived "wrong" which has been committed.
(2) Making cannabis (or anything else) illegal creates a black market, which leads to all sorts of trouble. The price of the product skyrockets, creating a huge incentive for the only potential suppliers: people who are prepared to break the law. Hence the association between cannabis and criminal activity.
When you see a news item about drug dealers defending their patches with guns, it's not because the drug is "bad", it's because the drug is illegal. If cannabis was legal and music was illegal, then gang houses wouldn't be concealing hydroponic dope patches, they'd be concealing CD copiers.
(3) Cannabis policing and prosecution is outrageously expensive, and the end result is often sending people to jail so they can learn to be better criminals. The resources which go into this exercise are staggering - enough to buy a whole lot of drug education and rehabilitation.
(4) The purpose of making something illegal is to prevent a minority of individuals from behaving in a way which is not acceptable to the majority. I don't believe that a majority of New Zealanders disapprove of moderate cannabis use. My evidence may be largely anecdotal but it's strong enough to convince me. Throughout my adult life, I've found that responsible cannabis use is extremely common. That's not surprising given that much of my time has been spent associating with musicians and other stereotypical druggies, but I've also worked with doctors, lawyers, accountants, television presenters, and people from many other "respected" professions. It's everywhere.
Of course, television presenters are far less likely to publicly support cannabis law reform than are unemployed musicians. The fear which goes with admitting to drug use prevents many people from speaking their minds. Consequently, when you see a rally for decriminalisation outside parliament, you don't see many lawyers in the crowd. You see people from a completely different socio-economic group. This, unfortunately, reinforces the stereotype of the "druggie".
Some other myths about cannabis:
Some other observations:
What to Do Then?
I don't actually think that cannabis should be legalised immediately (if at all). I think it would make more sense to proceed with caution and begin by de-criminalising it. It would still be illegal, but without the terribly unfair punishment of a criminal offence.
The bottom line is that prohibition doesn't work. It didn't work with alcohol and it doesn't work with cannabis.