I thought I might throw out an opinion on the topic of weed in America on account of it being 4-20. Side note, the reason 4-20 is "Weed Day" has nothing to do with weed really, it is Hitler's birthday. The whole getting high to "honor" Hitler was a giant joke.
Weed, and I cannot say this flatly enough, should not be criminalized to the extent it is currently. It should not be as ubiquitous as caffeine or saturated fat, but it sure as hell is not something people should be going to jail over.
The sanest way to look at drugs is through criteria and then weigh it against societal norms. Basically find ways to measure Weed against the drugs humans use every day: Caffeine, Nicotine, and Alcohol. I have 4 criteria.
1) How likely is an overdose in the course of regular consumption? You can overdose on Cocaine or heroin the first time you use it and die instantly. Proper use prohibits this, but that doesn't stop people from doing it. Currently you would die of smoke inhalation before you ever died nicotine poisoning, and drowning in coffee is more likely than caffeine overdose, alcohol is another story though. People drink themselves to literal death everyday because this shit is dangerous, and available in cheap high concentrations.
How does Weed compare? Well, the difference between Drunk and Dead with alcohol is about x5 or x10, so if you are drunk at 5 drinks, 25 will kill you. Marijuana requires about 40,000 times the exposure. So, much like cigarettes, you would die from the smoke (or the towering inferno) before the drug actually got to you.
2) How likely are you to become addicted? Again with things like Crack, close to 99% of people who use it more than once, will become addicted; opium (even prescriptions, Oxycodone being one of the most abused prescription drug in the country right now) are dependency machines, rewiring brains to have a constant need for them after a steady period of use. Nicotine is highly addictive, one of them most addictive of all drugs, with most anyone hooked after only two cigarettes, I imagine half of the lobbying money that goes into keeping cigs legal comes from the industry to treat addictions to them, the gum, patches, and various things to chew on (like the pen cap industry). Alcohol is less addictive, ringing in at about 1 in 13, or 7.6%.
How does Mary Jane measure? 10% roughly. It is hard to get real test data because doing a substantive study on Weed is looked at by the United State's Congress like disposing of Toxic Waste near pre-schools. But what data there is gives Weed a comparable measure to the drugs that are already in the system. If the differentiation is arbitrary, and can't be justified compared to other parts of the policy, then it is unjust and the law shouldn't exist.
3) What is the long term harm to a user? Alcohol kills people by inches, contributing to every negative condition a human can get (if you want to bring up the glass of red wine argument, that benefit has nothing to do with the alcohol, it has to do with grapes, if you ate a shit ton of grape skins, and didn't take the alcohol you would be better off still). Smoking causes cancer not just to the user, but to those around them, contributing to the overall indoor and outdoor air pollution that is becoming a major health problem for the whole country. Caffeine mostly just causes ulcers and the shits.
What about the Ganja? Basically, all of the effect of smoking cigarettes. The real issue is regularity of use, and how it is consumed. Eating weed brownies dodges the smoke issue, as does using a vaporizer because you aren't breathing in heavy wet smoke, just the drug in a gas form. The real problem is sexual, it lowers sperm production, motility, and the ability to get it up at all. Weed makes every part of a person lazy. That is what it does. I would like to posit however, that this is not as bad as sclerosis of the liver.
4) What is the ambient damage to a user? This goes to how bad the use affects family structure, and a person's ability to go about their day to day life if they used the drug. Alcohol is the king of this problem, ask any police officer, alcohol is fuel on the fire. Alcohol might not actually cause crime, because there is still a moron who drank and drove, or drank and punched, or drank and shot, but there was a reason the temperance movement existed in America.
How about the green? People are arrested for having it. People are arrested for selling it. People are arrested for growing it. Not a lot of people beating their wives after hitting a bong. Driving: Hell Yes. People drive stoned because they are stupid, just like the morons who drink and drive. But people who smoke weed are not taking a depressant in the same sense as the drinker, it is a relaxer, a duller, a mechanism of sloth and non-productivity.
I am currently considering my Masters thesis related to the drug trade and drug policy, because the organized crime wars in Mexico and Central America are big news and likely to get me a decent job, and these are the sort of criteria I would like to study to determine whether drugs are really the economic and social burden that they are made out to be. Prohibition and the Opium Wars have a very different context in modern hindsight then they did at the time, and modern healthcare has the potential to gather more information on the use of drugs than any point in history. So while I have very little to go on, I am going to make this very broad statement with the information I have, Weed is no Opium, in fact, Weed isn't even as bad as Alcohol, and America drinks that up. A new perspective is needed.
Lastly, a disclaimer: marijuana is a substance I have never tried, along with other drugs in general. I am a straight laced killjoy and have never had any desire to take anything. What is more I am fairly certain that other people take drugs in order to think like I think, so if I were to take drugs I would either cancel out and lose my mental super powers, or I would become to me what I am to normal people, Josh^2 and would probably get some form of telepathy. Either situation is probably not good.