One reason is that people (like me) don't want to further legitimize something they want society to discourage. I am strongly against drug use, and believe it sends the wrong message to impressionable kids to make it (more) legal.
Besides, in practice, your idea of right and wrong does not match the law anyway. Romantic relationships, for instance, are largely unpoliced. if you think marijuana use is wrong, then smoking marijuana just takes its place alongside sleeping with your friend's girlfriend, pretending to be in love with a sensitive, conservative girl so you can fuck her, and lying to your girlfriend about seeing other women as something that is deeply wrong but best left legal. Not to mention all the behaviors that are self-destructive but legal: excessive alcohol consumption, drinking sugary beverages, watching infomercials, etc.
The mismatch between law and morality, and the enormous overlap between legal and self-destructive behaviors, can never be eliminated, nor even reduced much. It's obvious to every child by the time they're teenagers, if only because basic civic education teaches skepticism of the law. Of the three dramatic internal struggles than define American history, the American Revolution, the Civil War, and the Civil Rights movement, almost every American sides in two out of three cases with people who refused to comply with unjust, oppressive laws. (It's irrelevant that which two is still sadly controversial.) We're also taught never to be afraid to be in the moral minority. Even when a matter is not weighty enough to justify rebellion, even if it is best for the sake of civil unity to appear to comply and to bow to the law when caught, it is always imperative to make our moral judgments independent of the law. We can be morally taught or advised by others, but we never put our moral judgment up for a vote. I'm sure you agree with this, and I'm sure you will or do teach your kids this if you have them. So what's the big deal about marijuana? It's just one of a thousand legal things you will have to teach your kids not to do. It's still legal to undermine a girl's self-esteem so she'll do things for you sexually that she really doesn't want to do. Hey, it's legal, it's popular, why not? (Well, you won't teach your kids explicitly not to do that, but it will follow from the basics.) Sometimes it's pragmatic to bring law and morality into line, and sometimes it's a huge distraction and waste of money to try.
If you're nevertheless determined to cultivate respect for the law as a moral institution, you should still be in favor of marijuana legalization. Marijuana is less harmful than alcohol, and making alcohol illegal is not an option. Therefore, the illegal status of marijuana will always be a glaring advertisement for the arbitrariness of the law and will continue to turn almost every college kid -- even me, who was never much of a fan of marijuana -- into a willing drug criminal. Thanks to pot, I now feel pretty comfortable with the fact that some of my friends have dealers, and that if I want some kind of illegal drug, I'm just a phone call or two away from being introduced to a drug dealer and making a purchase. It doesn't seem weird to me, and it doesn't even seem very dangerous. Aside from speeding and failing to come to a complete stop before a right on red, smoking pot socially is the only way I'm comfortable breaking the law. Every time I'm offered pot at a party and say, "Sure, why not," I'm reminded that laws are often silly and arbitrary, and I become more comfortable being a criminal. Many Americans approve of that attitude, but it sounds like you do not, so why do you support a law that undermines respect for the law?
It just seems like laws should be for things that we think breaking will undo the moral fabric of society more than denying people freedom will. IMO, this drug doesn't meet the bar.
Why are you strongly opposed to letting individuals decide what to put into their body? Are you also strongly opposed to alcohol and tobacco?
I just don't understand why many people opposed to marijuana are OK with alcohol; drunks are more likely to speed, brawl, and generally behave poorly, while stoners are more likely to drive 15MPH, munch on snacks, and generally chill out.
The thing is, prohibiting things just makes them seem cooler. For example, 80% of new smokers start before the age of eighteen. Few people would sign up to an expensive habit that smells foul and gives you cancer if not for the lure of the forbidden.
[1] Although to be fair, I'm even less of a fan of governments telling people what they can and can't do in the privacy of their own homes.
Extending the metaphor, tobacco smoking rates have fallen to new record lows in the US. Not via prohibition, but through taxation and education.
Maybe 25% of the population has smoked weed, and yet these people for the most part aren't facing any penalties. If you are going to have laws, you need a force that is able to enforce those laws, otherwise those laws are a joke and the government is a joke.
Legalizing marijuana is just the state coming to grips with reality. All criminalization has done is cause most generations to thumb their noses and defy a majority of laws that are on the books.
Source: http://drugabuse.gov/infofacts/marijuana.html
42.4 for older people
Source: http://www.plosmedicine.org/article/info:doi/10.1371/journal...
Suggests it's 12.3% in the US which I find more believable.
The study you cited seems to ask "...EVER used". Which could just mean took one puff once when very drunk.
http://www.erowid.org/psychoactives/statistics/statistics_ar...
Where does it end though? If the government can regulate what I do with my own body when it comes to drugs, why stop there? What about dangerous sports? Dangerous eating habits?
Should the governments prescribe a set of "safe" sports? Or approve a range of "safe" foods to consume? How about unsafe sexual practices?
If you answer "no", then how are drugs different?
In fact the big problems stem precisely from the attempt to control drugs, creating artificial scarcity and consequently high prices that lead of organized crime serving the market.
On the other hand, the war on drugs is destroying Mexico, and is not stopping drug use here in the States. I just don't think we can afford the drug war's costs (social, foreign policy, and monetary) any more. If you can't teach your kids to stay off drugs, I'm sorry, but they're on their own, as far as I'm concerned.
Edit: I don't live in California, and haven't looked at Prop 19 in detail.
But keep in mind I'm a libertarian, and I generally support locking people in cages in fewer circumstances than the average member of the population.
Thanks for sharing your contrary opinion, davidmurphy. :) Can you explain why you're against drug use, specifically marijuana (not the harder drugs)? And are you against alcohol as well?
EDIT: lol, I write the post and he goes from -1 to 4. Ah well. :)
Don't be under any illusions. What you advocate justifies the continued perpetration of horrors on people who were once children.