Maybe they are tired of going to jail for no good reason?
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.
[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".
> "the science says" card
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...
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.