I am not asking why people want marijuana legal, I am asking what arguments people make that legalizing marijuana would be beneficial to a society?
A government could potentially benefit from increased revenue if they tax the production and sale of cannabis, the legal cannabis industry is already worth billions of dollars.
Making it legal would also make criminals who supply the drug redundant, so they would make less money. The demand for cannabis is known to have driven a substantial amount of criminal activity in Mexico, the industry is so large there that criminal gangs can afford to be better-equipped than the police.
There is also the potential for research gains to be made. It's already known that this drug has some level of medicinal use, and if it were legal there is the potential that the field of medicine could learn from it.
Finally a government may just decide to make it legal in a bid to secure votes, it's not the most principled thing to do but similar things have happened before.
To put it into points:
- It lowers the cost of having the 'drug' policed. No need to have officers doing drug busts, arresting people, court cases, putting them in prison where food and 'living' costs need to be accounted for.
- The medical benefits compared to prescription(pharmaceutical) drugs.
- Tourism benefits from people who would like to experiment and have a little fun but it is illegal in their own state/country.
- The tax gains of the product to the state.
- Possibly advances in so many fields that could create jobs and huge amounts of income. Marijuana does not only need to be smoked(or consumed by the human body) but it can be used to make oils for numerous applications, hemp can make rope, clothing, paper and so on.
- It grows faster than conventional trees and has less impact on the soil which it is grown in, thus meaning more end product can be produced quicker and easier using the same field with less impact on the environment.
- Legal marijuana will be regulated. This means customers will get higher quality products.
- Prices will drop because production will be cheaper and there will be no penalties for production/distribution.
If you look at when and why the marijuana first became illegal the real question should be why has it taken so long for it to become legal again.
Because legalisation benefits health. Here is how.
Governments may want to legalise and tax marijuana in order to reduce consumption of soft-drugs and hard-drugs.
For an example, look to The Netherlands. Marijuana is decriminalised, and consumption rates are significantly lower than in the United States (for example, see Reinerman, 2000).
Indeed, a higher proportion of people have tried marijuana in the U.S. where millions have been arrested for it than in the Netherlands where citizens may buy it lawfully.
Moreover, in places where marijuana is legal, suppliers of marijuana are distinct from supplies of more dangerous drugs. When both are illegal, people may try marijuana, conclude that it's not as bad as they were warned it would be, and go on to purchase heroin from the same supplier. When marijuana is legal but heroin is not, and authorities are honest about the relative risks, marijuana consumers are less likely to wish to attempt heroin, and even if they do, it will be more difficult to get by (because marijuana sellers won't be stocking heroin).
But here, too, the evidence from Dutch surveys is heresy: despite lawful availability, the majority of Dutch people never try marijuana, and most who do try it don't continue to use even marijuana very often, much less harder drugs.
So, in summary: governments may want to legalise marijuana to benefit health overall. Research shows that legalisation of marijuana may lead to a reduction in consumption of marijuana, and if it was a "gateway drug" before legalisation at all, it won't be after legalisation.
Note: it might be debatable whether legalisation really would reduce consumption in other places as well, but whether or not it actually would, it is certainly an argument that can and has been made in favour of legalisation.
When something is made illegal it is then automatically pushed underground and then there is crime to commit. The problem is that making such a product illegal doesn't remove the demand for it, and people are going to insist on getting their hands on it whether the government has deemed it "legal" or not. Drugs will never disappear unless, and until, we address the psychological reasons people want to get high.
Making a thing illegal literally creates crime, and the "war on drugs" has been a disastrous waste of time, resources and billions of taxpayer dollars. It has only made matters worse in nearly every regard.
The prison system has also ballooned beyond belief as a result. Drugs are only a criminal issue because they've been outlawed, when in fact they are a psychological health issue. Instead of offering these people psychological and emotional help in dealing with life's struggles, they are simply thrown in prison, where they end up learning from other criminals how to be a better criminal. See the vicious cycle this creates?
Happy and healthy people have no need or want for drugs because they have no negative painful mentalities they need to escape from, or they at least have the knowledge of how to deal with inner pain. Therefore, education and teaching the choosing of happiness within despite life's circumstances is the answer. Banning the substance does nothing.
The one argument that I feel supersedes all others, yet is hardly discussed is that fact that other people do not have the right to tell other people what they should or should not do. Hold people responsible for the consequences of their actions.
If people drive drunk or while under the influence of drugs then hold people accountable. If people steal from others to support their drug habit then hold that person accountable for their action.
This ridiculous war on drugs is fueled by hypocrites of the highest order. "Ban this because I don't like it but don't ban this because I do like it". One cannot argue for the "War on Drugs" without saying ALL potentially harmful substances should be banned. That includes alcohol, caffeine, sugar, etc ... anything ... that could possibly be harmful. You should also make it illegal to be in a bad or distracted mood because that affects your driving ability.
It is our right as individuals to make our own decisions, however, that does not preclude us from being held responsible for the consequences of those decisions.
Other reasons for "society" to legalize drugs (if you need them) ...
1) End the supply chain from criminals. The drugs themselves are cheap. It would not longer be worthwhile.
2) Layoff about 50% of the police force. No more bloated tax-payer funded pensions. No more militarized drug raids. Far less corrupt cops (if such a thing exists).
Let's consider just one aspect of the legalization question - the success of the "War on Drugs" launched by the Reagan administration in the 1980's. This war has resulted in vastly increased policing and customs costs over the past 30 years, easily mimicked by the criminal groups supplying the demand because the price demanded is willingly paid by the consumer.
In the history of the world, no government has ever won a war where it's own people are paying all the costs of both sides. It is logistically impossible to do so because the other side simply runs the costs up so high as to bankrupt the governments fighting the war. Does this sound familiar yet? Michigan has gone bankrupt. The Federal government has had an unprecedented level of acrimony over the budget, and runs most of the year on interim bills paying only essential services. Illinois can't pay lotto winners.
Governments eventually realize that the more popular drugs must be legalized, moving their control from criminal to medical personnel, as the only way to stave off inevitable bankruptcy.
From a very liberal (maybe libertarian) perspective, there is the simple argument that it is not harmful enough to give a government the right to prohibit it - it is not a weapon, not something necessarily harming others or the environment when used or made, not a tool only useful for causing someone else illegal damage.
Good answers all around, especially from BossRoss. I want to focus on a different type of answer, a counter to the implication within the question that marijuana should be illegal in the first place. And for the record this answer is coming from someone who does not wish to smoke marijuana and frankly would be happier if others didn't as well; I just don't think it's justifiable to make it illegal despite this fact.
Lets start with stating some specific axiom I personally believe and I hope you won't debate. If you disagree with them then the rest of the answer is meaningless.
- Government laws should be written to minimize harm whenever possible.
- A law which restricts one's actions or choice removes some degree of their freedom and expression, and as such does some form of harm to them. (this is not specifying how much harm or claiming that the law should not be enacted).
- An individual should be presumed to be striving towards their own happiness and the one best capable of measuring what action will best lead to that happiness unless demonstrated otherwise.
- In the event that all choice leads to harm we should choose the action that does the least amount of net harm.
- Arguments have been made by other answers that making marijuana illegal does some form of harm (you can debate how much, but some minimal amount has been presented)
From these three axioms I would draw two basic theorems
The harm of allowing marijuana to be legal must be significant enough to outweigh both the direct harm caused by it's illegality (ie, all the other answers to your question), and the implicit harm of enacting a law that lowers one's freedom to justify it being illegal instead of legal.
If an action only does harm to the perpetrator of an action we should presume he is doing it because he believes he will benefit from it and should not enact a law to prevent it until that harm is substantial enough to make us doubt their decision making ability. Basically, this is why we allow people to eat unhealthy food, smoke, or play physical sports with risk of injury; though your welcome to debate what degree of harm is sufficient to justify enacting of a law.
Corollary: if the harm to the individual of smoking marijuana is sufficiently low we should presume they are capable of deciding it is worth the potential harm.
I would argue then that the as of implied but not discussed factor comes up in my first theorem. There is a presumption in your question that marijuana does significant harm if legal, enough to potentially justify the stated harm of making it illegal. I believe that the actual harm of legality is low, low enough that it can not outweigh the harm of illegality, but that most people in the US have been lead to think of this harm as significantly higher. I think this results in many supporting illegality not because they have not heard or don't understand the harm of illegality, but because they have misjudged the harm of legality in my first theorem they still, falsely, think it outweighs the harm of illegality.
To address that I need to go into some history of the drug and how it's effected our view of it.
Marijuana was first campaigned against using a number of yellow journalism campaigns. It's believed these were inspired due to fear of it as a crafting material, replacing wood pulp and nylon, which made certain individual who's profit came from these materials want to see marijuana regulated so it couldn't provide competition. See the campaign ran by Harry J. Anslinger on wikipedia.
The most relevant aspect to our culture and legislation for marijuana comes from the gateway drug theory. Studies showed a huge percentage of users of hard drugs (like cocaine) had smoked marijuana earlier in their life. This lead to the theory that marijuana was a gateway drug that lead to people using hard drugs. By this reasoning it made sense to outlaw marijuana because the harm that would be caused if it lead to an addiction to harder drugs was indisputable large enough to warrant legislation.
The problem here is that this was a pretty blatant misuse of statistics and causation vs correlation. If you think about it anyone willing to use a drug as dangerous as crack probably has no qualms using something as safe and easy to get as marijuana. Thus by interviewing addicts they were picking a group of people who's very disposition for both addiction and violation of the law made them likely to use marijuana and comparing them to a group of people who were not prone to addiction, it was not a fair comparison.
Later studies have done this in a better manner, looking at marijuana smokers and seeing how many of them also used crack, and later longitudinal studies to look at people who started using marijuana at a young age to see if they ended up switching to harder drugs later. These better implemented studies showed that marijuana use did not have a significant effect on later harder drug use (in fact, I've always been shocked how little a correlation there was, since there is still a sampling bias here that should find a mild correlation to harder drug use, I'm really shocked there wasn't really found to be any correlation).
The point being that the biggest argument for controlling marijuana, the claim that it lead to use of worse drugs, was pretty much proven to be false, and most statisticians and researchers seem to agree on that fact today.
Finally, the laws for deciding how harshly marijuana should be punished that are in effect today were developed by asking an 'expert' how dangerous marijuana was compared to crack and setting a ratio of years in jail relative to that danger level he stated. The problem is that this 'expert' admitted later in life to having made up the 'danger' ratio on the spot without any research and it's argued that the number he made up was an extreme over exaggeration of the risk factor. If true this would imply our current punishments are disproportional, as their proportion was based off of a disproportional claim of risk.
The point for all this history is to show that our public view and depiction of marijuana is heavily slanted by misinformation of the past. Poorly done, or entirely made up, research and all started from smear campaigns to give marijuana a bad name based off of economic benefits.
When assessing the danger of marijuana in the modern era you need to try to ignore the impressions you have been given from media, and look at the hard facts, because the cultural background is heavily tainted by these above flaws.
So lets look at the hard facts, what harm does marijuana do?
Technically marijuana is physically addictive... technically. To be exact it's about as addictive as caffeine, arguably less so. So there is a physical addiction, but of such trivial levels as to be a non issue. Technically one would get mild headaches for a week or two if they stop using marijuana for a little while (and yes, I did experience this when I gave up caffeine, and no it was not anywhere near bad enough to make me feel I needed to start taking caffeine again).
It is far less addictive than alcohol, an important point of comparison I'll get to more later.
In short there is a minor negative affect to addiction. I would argue, even ignoring all the other arguments above, that if this was the entirety of the issue with marijuana it should be made legal on the grounds that freedom of choice, even bad choices, should be favored if the harm is minor enough; as shown by our legalizing of other equally or more addictive drugs.
Short term harm to smoker
The short term harm (the harm suffered within an hour to a few days after from having been high) of marijuana is pretty minor. Those who smoke it generally feel the desire to sit around home and do nothing. This is a waste of time and productivity, which is a harm, however, it generally means that they likely aren't going to go out and do anything stupid or reckless that will endanger or harm them, they lack the motivation to do so while high.
It can impair ability to learn, problem solving, and motor skills, meaning that pretty much any activity done while high is going to be less effective than not being high, though the effects are generally not as severe as to make one incapable of performing an activity, just less skilled at it. This could lead to harm if one is trying to perform an act that is dangerous if done when impaired, most obviously driving, which I will get to in a bit. However, the fact that the biggest effect of pot is to make one feel the desire to sit around and 'space out' means that most people who are high are not going to try doing anything potentially dangerous, limiting the risk.
It should of course go without saying that any particularly dangerous activity, like driving, should still be illegal while high, to protect the smoker from such mistakes.
Back to our alcohol comparison, All form of impairment above are equal to or less than those suffered from being drunk. In addition alcohol tends to also impair judgement and impulse control. So while pot smokers are left inclined to sit at home doing nothing drunks are left inclined to go out of the way to do extra dangerous things they would never try sober. This means drunks are far more likely to do something foolish or stupid that will harm them. Alcohol also can increase aggression, leading to more fights and self harm from such.
Larger doses of marijuana can lead to confusion about location and loss of memory, depression, and anxiety. From what I can tell these require rather high doses of marijuana that are rarely consumed, but I'm not really able to find statistics on this fact and I'm hardly familiar enough with the drug-culture to say personally.
Again, alcohol causes all of the above in large quantities. However, at large quantities alcohol can lead to overdose, alcohol poisoning, and severe bodily harm or death. So of the two I would rather see large quantities of marijuana use than alcohol. Alcohol also causes higher degrees of depression and causes depression even at lower consumption levels.
Finally, alcohol causes a hangover, which causes both physical suffering and impairment of everyday activities the day after, which marijuana does not do.
The point being, marijuana short term negative symptoms are mostly either the same as alcohol or less severe. However, in addition to those short term symptoms shared with marijuana alcohol use leads to other, far more sever, harmful effects increased risk taking at low dosage and death at high dosage meaning it's far more lethal to the user in the short term.
Short term harm to others, and DUIs
Of course the bigger question is the harm done to others if someone is high. Again, for the most part marijuana smokers are unlikely to cause trouble because they tend to stay home spaced out in a safe location when high, the whole lazy apathy part of marijuana is a great way of avoiding most of the risks of the drug; but some harm would still no doubt occure.
The harm to others from marijuana would come from impaired skills when doing dangerous activities, and by far the most obvious of this being driving. Marijuana smokers can be involved in DUIs, and this does put the public around them at risk. This is the biggest argument against marijuana legalization by far!
However, the DUI is not as bad as it seems (still defiantly something we would prefer to avoid). It turns out that while reflexes are impaired when high it's not as drastic and is not as dangerous as one may presume. One study I found suggested that driving with a BAC just over the legal limit was 4 times as dangerous as driving while high. The most telling implication of this is that driving with a BAC just under the legal limit is still more dangerous than driving high despite being legal.
Furthermore, drunk individuals are FAR more likely to choose to drive under the influence than someone who is high, and not just the apathy affect I keep bringing up, though they still apply. Someone who is high is still capable of making the conscious decision to not drive under the influence, because their judgement has not been impaired! Furthermore, since drinking tends to be associated with social get together and bars people who get drunk are more likely to do it away from home and then feel the need to drive home, leading to social influences that encourage drunk driving. All of this combines to suggests that a drunk is absurdly more likely to choose to drive under the influence than someone who is high. Again I stress, someone who is high still has about the same judgement ability and thus is able to choose not to drive while impaired, there is no reason to think that allowing someone to get high will immediately lead to a significant increase in DUIs.
Furthermore, it has been suggested that some people who currently drink socially may switch to social marijuana use if it were legal. Since social marijuana use is unlikely to lead to DUI for all the reasons above, and DUI due to marijuana less likely to lead to actual accident, this could remove a small number of drunk drivers and alcohol related accidents from the road by replacing them with people who are high but able to choose not to be part of a DUI.
In fact, the sort of people inclined to be part of a DUI already drink, the number of people that do not drink but are predeclined to make the sort of decisions that lead to a DUI is small so the number of people who would have been involved in drunk driving before switching to pot could very well rival or surpass the number of non-drinkers who start smoking pot that are inclined to be involved in DUIs. With the decreased risk of DUI while high compared to being drunk the net result of moving some people to alcohol could mean that there would not be an increase of DUIs with legalization then there is without it. Once you include the fact that driving high is four times safer then driving drunk it's even possible that the number of car crashes from DUIs could decrease by legalizing marijuana.
Going back to our alcohol comparison, drunks can cause harm in ways other than DUIs. Again the general impaired judgement and risk taking can lead to foolish stunts which could put others at risk as well as the drunk himself, like deciding to discharge a firearm for some insane reason while drunk without thinking about who may be hit. Drunks also are more prone to violence which can lead to fights which harm others. Alcoholism is closely linked to domestic violence for similar reasons and is believed to greatly exasperate the problem. All of these are problems that do not occur with marijuana use.
Long term consequences
This is a subject that would take too long to dive into. The studies on long term risks of marijuana are not as good as with other common vices, due to the difficulty of getting subjects. There are definitely some long term effects, cancer and breathing problems are the biggest risk to the smoker, while birth defects may also be a risk if someone smokes while pregnant (though I haven't found anything too conclusive about the last?). These are undesirable side effects for sure.
However, the effects are minor, far less than both alcohol and tobacco use. While marijuana is linked to all of them so far as I can tell it is a minor factor in most cases. Unlike the massive link between smoking and lung cancer marijuana use has not been conclusively linked to many types of cancer. It has been linked to some, but was only a very minor contributing factor.
Lung and breathing problems are drastically smaller than smoking, again generally are not as severe, and may in fact be mostly exasperated by impurities in illegal marijuana that can be avoided with regulation. Properly regulated pot would likely not have significant health problems.
The birth defects is the most concerning to me (as it harms someone else rather than yourself) but I can't find much on the exact risks here. Those who reported only occasional marijuana use while pregnant did not show any conclusive increase in birth defects. Heavier marijuana did seem to have a small increased chance in birth defects. However, those who used marijuana were more likely to have other dangerous risk factors (lower income, criminal activity, use of other substances like alcohol etc), so even those small increased risks could not be conclusively linked to marijuana without better controls. As I research it more it sounds like the whole belief is "marijuana could be harmful, best to avoid it", but with little affect... in fact it sounds very similar to the sort of research I saw when I tried to determine rather heavy caffeine use could lead to birth defects.
In short most of the long term effects of marijuana have little effect or are not even conclusively proven. This is not to say it doesn't do harm, it does, but so far it seems that the long term harm is pretty minor, and in fact some of the believed harm could very well be due to sample bias since marijuana smokers tend to have other risk factors. In any case the risks are far far less than legal options of alcohol and cigarettes. I will caveat all this by stressing there are less reliable research, we could find that things are more or less dangerous once it's legal and can be easier studied.
Oh, one other 'long term' effect is that it lowers fertility while regularly smoked, by a non-trivial amount. However, fertility comes back once one stops smoking it for awhile. Some would consider this a benefit (free quasi-birth control!... hopefully not the only birth control used). I don't consider this as significant since one can always choose to avoid marijuana while trying to conceive the same way it's recommended to avoid caffeine and lose weight (for women) when trying to conceive.
Marijuana just doesn't do all that much harm. It's far less dangerous than legal alcohol, I would much rather a society where alcohol was illegal and marijuana was legal if I thought we could do it (prohibition has proven we can't). To argue marijuana is so bad that it should be illegal requires arguing that alcohol must be made illegal, it's pretty hard to justify allowing the one that is 4 times as dangerous.
While marijuana does do some harm, and I personally would not encourage anyone to use it!, the harm is minimal and is mostly limited to self harm. We have consistently agreed that there is a certain point at which freedom of choice means allowing people to choose stupid actions. I'm not convinced that the harm done, short or long term, by marijuana is significant enough to justify infringement on ones right to choose, especially when worse alternatives are allowed.
While I consider the DUI threat, the risk of others being harmed by another use of the drug, is the biggest argument the fact is that it's unproven that legalizing marijuana would actually lead to more DUi related accidents. In fact as far as I can tell there has been no noticeable increase in DUI-related accidents in states that did legalize it. There have been more marijuana related accidents, not surprising with more use of it, but again this could be counteracted by fewer drunk drivers as previous drinkers switch to marijuana use. In fact since Alcohol has other negative consequences on others, it's possible that marijuana legalization would lead to less harm to third parties by moving more people to 'safer' alternatives.
I personally do not encourage anyone to use marijuana, I would try to encourage my children to avoid it. However, The harm is actually so minor I can't say I would be willing to justify infringement on others rights to choice by make it illegal. Once I factor in the benefits everyone else has already listed to legalizing it, most relevant to me the excessive punishment of it, ruining lives of smokers for a minor offense and costing tax payers extensively in both the war against it and in paying for prison time (the majority of prisoners are in for non-violent drug related charges, and most of those are for marijuana), and it seems the harm of making it illegal far out weighs the harm of legalizing it, even if I don't want anyone to use it.
I live in the Netherlands, a country where Marijuana is legal. It works great in the Netherlands, like stated before people use less drugs over all, people turn less often from softdrugs (like Marijuana) to hardrugs (like Herione).
Marijuana is not healthy, but as stated before it's healthier then alcohol and tobacco. It's less addictive then tobacco.
Selling Marijuana supports a lot of criminal activities in countries where it's not legal.
There are more possiblities of controlling and informing about Marijuana use when it's not illegal.
In the Netherlands a lot of teens educate themself about the kind of effects different drugs have. It's not taboo here to talk with your parents about drugsuse. It's good that a conversation is possible.
Marijuana being illegal is a violation of the spirit of the constitution of most Western democracies. As pointed out in most answers given, it's not harmful enough to justify banning it. Many people point out that legalization of marijuana will be a net benefit to society. But the argument based on the spirit of the constitution of democratic countries is a separate argument, it doesn't depend on there being any net benefits to society or personal health.
Simply put, the government shouldn't have the right to overrule personal choices, even if your personal choice is not good for you, provided what you choose to do isn't disruptive to society. Here "disruption" has to be defined in a reasonable way consistent with legislation on other matters. Any restrictions to deal with potential disruption of society should aim at keeping options for exercising personal choices open as much as reasonably possible.
Among the benefits to society are:
The advantages of cannabis itself, (a mundane and valued ingredient of the U.S.'s pharmaceutical armamentarium prior to 1937).
Reduction of and discontinuation of historically prolonged policies of covert racism and national disunity. The banning of cannabis was spearheaded by bigoted covert racists, who regarded the immoral strategems of Jim Crow laws as less evil than what they imagined to be the greater horrors of tolerance. Racists reframed Americans view of cannabis with one word, "marijuana", cementing cannabis to anti-Mexican racism and nativism. De-framing cannabis is a blow against needless disunity.
Improved respect for Police. Enforcing once-glamorous laws now considered ignorant, (even by police themselves), reduces the dignity of the office.
Similarly improved respect for Judges, themselves ashamed of being compelled to dispense unjust sentences.
Less hypocrisy for citizens who indulge in cannabis, and less stigma for patients that take cannabis.
More personal freedom for citizens to air grievances against those who overindulge in cannabis. (A complaint against an obnoxious illegal indulger is invariably "involved" with considerations of legal overkill, or potential underworld reprisals.)
It empowers consumers to sue, and the government to prosecute, producers who wrongly attempt to market adulterated, counterfeit, or contaminated cannabis. Tolerating adulteration makes almost any market more hazardous, because consumers can no longer rely on a standard dose, and instead must experiment via trial-and-error.
An argument I haven't seen here yet is one from Australia, where some people want to grow hemp for cordage/fabric/seed/oil. Lower impact on the soil, less pesticides, good output, etc.
However, the police (understandably) don't want the hassle of testing and figuring out whether each particular plant is hemp (low tetrahydrocannabinol) or cannabis (drug-level, high tetrahydrocannabinol). So, legalising marijuana would make all plants with that leaf shape OK to grow and make hemp as much part of the industry as cotton and linen.
This argument is not about drugs per se, although the usual "if it's legal, there's more quality control and price competition/goverment-set low prices, so it's safer" are usually cited to cover the "dangers of drugs everywhere" point.
First of all, as other have stated, votes. Regardless of actual effects of the drug itself, the issue of legalization / prohibition is mainly an issue of people that see the marihuana use as part of a lifestyle they want / they do not want and that is what fuels the debate. Marihuana is far from being the only "recreational" drug, yet you do not see (many) people claiming for the legalization of, say, LSD or MDMA.
To answer what you could expect from legalization, you need to make some assumptions about the current state and the changes it will bring. Most people make implicitly the assumptions matching their beliefs and then answer, I'll be (dis)honest and make the assumptions explicit.
Marihuana has side effects comparable to alcohol and tobacco. Since the drug is illegal there are few studies, but some of them link its abuse to memory loss. And, given how similar it is to tobacco (in essence, both are insecticide-ladden plants, burnt and inhalated), some research suggests it may cause lung problems in a similar way.
Legalization will not cause an epidemic of "stoners". People who do want nothing but getting high usually already has the way to get marihuana. And, if they do not, they usually have access to cheap alcohol to get almost the same effect.
Now, the issue is if legalization has benefits that outweights 1). Those could be (note that some are less clear than some other answers make them appear).
taxes: both as a measure to avoid excessive consumption, and to provide funds to pay for the externalities (read: extra health care) due to its usage.
quality control: the product will be sold by legal producers, who will be accountable for its quality. Those producers will be interested in ensuring that their product is not made in some shoddy farm using contaminated soil/water but in good conditions. Everyone would be able to buy some weed and send it to a laboratory to analyze its quality.
less money for drug traffickers, as part of their business will just dissapear. I am not so sure about that, mostly because it is very difficult to assess (drug cartels do not expose their accounting to the public, because they are not publicly traded). Most likely, small scale weed growers/seller will go out of business, the more powerful drug organization will just increase their reliance in other drugs. If they can afford the "War on drugs" just by increasing price, they can react in the same way to this change.
less drug related crime. This one is mostly based in previous laws. For example, in USA there are lots of "criminals" that are just consumers, while in Western Europe possession of small quantities of drug, for someone's own consumption, has been decriminalized. Yes, legalization would reduce that number of "criminals" (and the costs associated, but public and personal). But you could also got the same result without consumption legalization by copying the laws from Western Europe.
So, mostly 1. and 2., a "maybe/improbable" 3., and 4. (but with other alternatives available to get 4.).
Note that I do not mention "research" or "medical" properties. That is because I consider those points alien to the legalization debate, and using them misguided at best and dishonest at worst. Drugs way nastier than marihuana (including methadona, heroine and other opium derivatives) are part of standard medical treatments; making marihuana a prescription drug is not an argument for marihuana legalization because that would mean being for the legalization of novocaine, morphine and all of the other nasty stuff.
Honestly, I am slightly pro-legalization myself (maybe with some rationing system), but anytime I see someone claiming the point about medicinal THC (or the one about using hemp for ropes and paper) makes me wonder if maybe marihuana actually causes that much brain damage.
While this may not sound like a "policy argument in favor of legalizing", pointing out the weakness of the other side's policy arguments also qualifies, the point being that marijuana access should not have to be defended against claims that appear logically unsound, unconvincing, and even more applicable to substances that remain legal.
The ban came about in the first place for political reasons more than a legitimate health concern, and the propaganda was pure fear mongering, leading people who have done research to see opponents as merely ignorantly reiterating the old lies on a pavlovian reflex upon hearing the label "drug" which is equally applicable to caffeine.
And many are, in fact, ignorant - such as the well-known example of former Polish Prime Minister Jarosław Kaczyński claiming "...marihuana must be fought, but is marihuana made from hemp? It's not, is it? At least I know nothing about it. Anyway, I don't know how you link marihuana with hemp, drugs must without a doubt be fought..."
You make an interesting choice in language.
"It seems to be absurd as it is a drug many people abuse."
Maybe so, but what are the harmful effects to society of that abuse? How do they compare to costs to society of prohibition of a particular substance, in terms of law enforcement, and opportunity costs from loss of otherwise productive members of society to our criminal justice system, either through incarceration or effects of having a conviction on their record? How much of the harm of abuse, for society, is because of the criminals who act as the supply chain (harm that only exists because of the illegal status) vs a legalized, regulated supply chain?
I personally can't stand the ubiquitous use of the word "super" instead of "very" or "really" and feel its constant use in this manner is an "abuse" of our language and my ears. But does my personal distaste for this habit mean that it constitutes a harm to society? If I wanted to impose legal sanctions just because I don't care for it, is that a proper use of the legal authority that a society can impose?
The main policy argument seems to be that the costs associated with criminalization, to society, are much greater than they would be if the substance were legal. It's also argued that there are some potential benefits that can not be explored because the drug has been categorized in at the same level as heroin or methamphetamine. Finally, since it's argued that the effects from use are relatively benign, even compared to legalized substances, and presents almost no danger to anyone else, there is the argument about personal freedom in matters that do not harm others.
The National Institute on Drug Abuse (NIDA) admits that cannabis is not physically addictive, it is not a gateway to drugs, it does not cause cancer or emphysema, there is no evidence it negatively affects driving, there is no evidence it causes an early onset of psychosis, and there is no evidence it negatively affects teen IQ
The most important of these is the fact that there is no evidence cannabis negatively affects driving, because the main argument against cannabis legalization is muh roads. It is the only reason anyone could claim to be a victim of cannabis consumption, yet it’s unfounded and doesn’t make anyone a “victim” anyway.
The second most important is that it doesn’t negatively affect teen IQ. This study was done after the popular “marijuana makes kids lose 8 IQ points” nonsense.
Here are some quotes from NIDA:
In NIDA’s article Is marijuana a gateway drug? it says:
“These findings are consistent with the idea of marijuana as a ‘gateway drug.’ HOWEVER, THE MAJORITY of people who use marijuana do NOT go on to use other, ‘harder’ substances.”
In NIDA’s article Drugged driving, they mention this study about cannabis and driving:
The study says:
“The more carefully controlled studies, that actually measured marijuana (THC) use by drivers rather than relying on self-report, and that had more actual control of covariates that could bias the results, generally show reduced risk estimates or no risk associated with marijuana use (Elvik, 2013).”
And it concludes:
“The results of this study are in line with the previous research on the effects of marijuana on the risk of crash involvement. While a number of previous studies have shown some increased risk associated with marijuana use by drivers, many studies have not found increased risk. As was noted previously, studies that measure the presence of THC in the drivers' blood or oral fluid, rather than relying on self-report tend to have much lower (or no elevated) crash risk estimates. Likewise, better controlled studies have found lower (or no) elevated crash risk estimates.”
In NIDA for Teens’ article Marijuana, they mention a major study done on teenage twins. NIDA says:
“However, two recent twin studies suggest that this decline is related to other risk factors (e.g., genetics, family, and environment), not by marijuana use itself.”
The study can be read about here:
It says there is no evidence that cannabis use with teens causes a lower IQ or any developmental problems.
The DEA factsheet for cannabis still says:
“No death from overdose of marijuana has been reported”
I would like to add to webworm answer.
Say you think ganja is bad for you and that gives you right to tell others not to use it.
What would stop other people from saying not worshiping God that tell you to pay them $1 million dollar is bad for you?
Many says that ganja, xtc, and acid are dangerous.
Guess what? They also said porn is dangerous. Yet 99% of men watch it and do fine.
All those drugs were once legal. Did we see mass IQ drops, mass suicide, or anything? The number of people that die due to xtc is like 5 out of millions of use. Those 5 happen indirectly.
If we start letting people prohibit stuff because they think it's bad for us, we start letting people rule us. It's our life. Why give power for others to decide what we can or cannot do? It's not toward our best interests to do so.
The same way, after years of trying to find fault on ganja, xtc, and acid, so far, no scientists ever found out that drugs are dangerous in long term in anyway. They're not even addictive.
It just shows how arguments are useless. Anyone can say this or that is dangerous and criminalize based on any reason.
Here, in my country, government don't just ban drugs. They pretty much ban everything. They tried to ban uber you know. At the end, consumers will do not matter. Businessmen that make money are businessmen that got bribed.
That's my favorite thought experiment. It ignores the cliches (conspiracy, health, etc) and reframes the question.