Really, what are these people trying to gain from legalizing Marijuana?
In absence of any compelling argument to the contrary, things are legal by default. There has never been a terribly convincing argument for imposing punishment for marijuana.
This slippery slope argument is decades old and isn't borne out by experiences with decriminalization or legalization in other countries. I'm not and never have been a user, but I see a lot more harm in criminalization than in legalization.
pulling "the science says" card out
Science is a trump card because science trumps. Seriously, people wouldn't constantly perform science if it didn't work.
You clearly are uninformed on the history of prohibition.
Producing, distributing, and selling remain criminal offenses.
Anybody who brings up the issue of the damage done to society by drug use has to then take into account the damage done by drug prohibition. It's clear (to many) that the latter is far more harmful.
But that shouldn't be the argument. Bleach is very harmful, but I'm not stopped if I decide to go drink some. The constant reduction in personal liberty by deciding what chemicals people may possess.
I can only hope someday this is viewed as backwards and horrible as governing what kind of sex consenting entities engage in. (In fact, this is still a problem, as sex with consenting adults of other species is still illegal in many jurisdictions. In fact, to my shock it seems this is going in the opposite direction, as The Netherlands recently criminalized such sex. I wonder how such laws handle cases where an animal rapes a human.)
At one time, the animal might have been given a trial in a court, just like a human. Google "animals on trial" and you'll find some interesting articles about specific cases and the practice in general, mostly from a "let's make fun of our idiotic ancestors" perspective, but there is one from Slate in there that takes a more nuanced look at why they did it.
There is an early 20th century book about animal trials and punishment called "The Criminal Prosecution and Capital Punishment of Animals" by Edmund P. Evans. It is available [1] at Project Gutenberg.
[1]:http://www.economist.com/blogs/dailychart/2010/11/drugs_caus... [2]: note Adderall ~= meth, morphine ~= heroine, tobacco, alcohol, you get the picture
So it's very unfair to allow only certain people access to basic medications, especially when the medicine itself isn't particularly dangerous. The study you linked has a rather expanded definition of "harm".
I wonder how many people that are pro-legalization are also pro restricting of say sugar, and putting limits on soft drink size (NYC style), etc...
> "the science says" card
Drug prohibition and the war on drugs has had an enormously deleterious effect on our society and our criminal justice system. It has resulted in one of the highest incarceration rates of any "free" country in history, for non-violent crimes where typically the "victim" in the crime is the person being jailed themselves. It has resulted in a massive change in the criminal justice system due to so many drug cases being prosecuted, and drugs being such a prominent target of police activity. The result is massive expenditures on police, DAs, and the courts and yet a constriction in the resources being used to solve and prosecute the most serious crimes (murder, rape, etc.) or to ensure justice is carried out according to the finest principles of a free and just society.
Moreover, drug prohibition results in massive amounts of money getting funneled to hardened criminals and gangs, because when the business of procuring and transporting drugs is illegal those are the people most willing and able to undertake such activity and most desirous of "easy" money outside of the conventional labor market. That vast wealth propping up criminal enterprises then serves to corrupt the criminal justice system directly, especially the police, through direct payoffs. Just as it did when alcohol was illegal.
Even when direction corruption isn't a factor, the militarization of the police has led to a massive degradation of freedom and personal safety as well as a growing divide between the law abiding public and the police.
Meanwhile, a massive section of the population, recreational drug users, becomes outlaws. They are forced into a more tentative or even adversarial relationship with the police and the justice system in general. They are more vulnerable to other crimes and less likely to cooperate with investigations. These are not just "fringe" elements of society such as destitute meth addicts on the streets, these are people who are otherwise fine, upstanding citizens. Folks such as Carl Sagan, Bryan Cranston, Morgan Freeman, and Bill Gates. These aren't people whose lives were ruined, these are people who chose to exercise their own individual liberty to explore recreational drugs, just as people choose to use alcohol, nicotine, caffeine, etc.
Overall, the war on drugs has been incredibly corrosive for liberty, the proper functioning of the criminal justice system, social cohesion, rule of law, and safety from violence. I can think of few things developments within the last century which have been more disastrous to the stability and health of America and the developed world as a whole, I think that says a lot.