The answer is simple but not easy to accept. First I will list the reasons and then I will offer an explanation as to why people will not readily accept such a change.
1) Reduce more serious criminal activity such as gun running, extortion, murders, slave trade, all which are funded and supported with drug money.
2) Put a hurting to organized crime by hitting them where it hurts, their bank accounts. Nobody will buy illegal drugs that are not tested, quality or price controlled when there are effective legal ones that are. This will force such organizations to either sell them legitimately to make up for lost revenue and thus expose themselves to government inquires into their financial holdings or try to continue producing, exporting and selling a product which has been severely devalued by a flooded market.
3) As I alluded to in number two people feel encouraged to purchase products that are tested and regulated. It makes them feel safe. This also means that such testing and regulation will inevitably lead to improved quality and effectiveness. Thus improving the over all strength and usefulness of products that otherwise would be of varying quality and risk. Anybody who doubts this should just look at the Tobacco and Spirits industries .
4) There is no legitimate reason why Tobacco and Alcohol should be legal and other recreational drugs aren't. People should be able to intoxicate themselves with the poison of their choice. Not just the ones that are "Nanny State approved." Consider that all of them are poisons that ultimately cause death. Who should have that choice, the individual or Uncle Sam?
5) More stuff to tax! That should make every one with a pork project happy and they can ease their troubled conscience by putting a portion of it to education of the deleterious effects of drugs (All of them!). They can also spend some of the taxes on rehabilitation instead of spending money on incarceration.
6) Studies have shown that people are less prone to engage in a vice if it is seen as sociably acceptable because it looses it's "naughty" factor. People like to engage in things that are perceived as risqué.
1) Now the reasons why people would never go for it is because there is a moral and social stigma attached to drugs. The Christian church especially has done a bang up job of making people believe that they are bound for hell if they engage in the use of recreational drugs. When the fact is people pick and choose their addictions every day and so long as it is not illegal the Church doesn't stigmatize or condemn the rest of those law abiding folks. People only hurt them selves when they abuse drugs, not God and God is merciful to the weak not vindictive.
2) The other reason is the misguided belief that we are winning the war on drugs, that somehow all the narco-traffickers are running for the hills. Where there is money to be made people will flock. The criminal elements around the world are winning because they have a gold mine in the drug business. Shut the mine down and terrorist groups and mafias and all kinds of low life will loose the biggest cash cow they have.
3) This one is probably the scariest of all and that is people are afraid of unleashing a genie they will not be able to bottle back up. The idea goes that once legal everybody and their mother will run to the local grocery store and buy a pack of cocaine lights. They are afraid that, if the experiment fails there will be a social revolt unlike ever before. When the reality is that a failure in this experiment would result in a bunch of junkies going through withdrawal not a national revolt. How many of you smoke or drink and have converted all their non-smoking and non-drinking friends, hmm? Exactly, none and that is the point that it is irrational to even consider that such a thing would even happen.
4) Then there is the thought that endorsing such a law means that you condone such vices. That couldn't be further from the truth. All vices have their varying degrees of addiction. There are those that use drugs within manageable limits and then there are those that are uncontrollable addicts. For these there needs to be health care and support none of which is possible when they are shooting up in dark allies under the cover of night. The fact is we don't have to worry of the user. We have to worry about the abuser. The truth is if you know and love an addict you will support a law that makes his addiction manageable and not criminal.
So there you have it. Tell me what you think. Pro or con lets start the debate.