Well, I agree with one poster here that there is no such thing as a 'perfect policy' when it comes to drugs and alcohol.
Over all, law is supposed to be the last resort for humanity. God instituted the Law so that Israel might live:
"Now this is the commandment, the statutes and the judgments which the LORD your God has commanded me to teach you, that you might do them in the land where you are going over to possess it, so that you and your son and your grandson might fear the LORD your God, to keep all His statutes and His commandments which I command you, all the days of your life, and that your days may be prolonged.
"O Israel, you should listen and be careful to do it, that it may be well with you and that you may multiply greatly, just as the LORD, the God of your fathers, has promised you, in a land flowing with milk and honey..." (De 6:1-3)
Israel knew nothing about God or living in freedom. The whole Exodus story is about the errors of the people that were so entrenched that only their death was sufficient to remove their bad thinking. They were 'too Egyptian' in a sense, used to living in a pagan culture with an oppressive overlord.
This is important to keep in mind: oppressed people, and people coming out of an oppressive culture, have difficulties managing self-control. That's because they are used to other people always telling them when to stop. There's always a boss around.
Christ brings a new paradigm: the indwelling of the Holy Spirit and the Law coming from within, driven by love rather than punishment. The Old Testament documents how God tries to stir love and gratitude among the people of Israel, but it seems impossible. Jesus Christ comes and says that in order for man to keep the Law as it was intended is an impossibility, and that only God residing in man can make this possible... through divine and perfect love.
I have written this before, but it bears repeating: the State is not about love. Government is about everything outside the limits of love.
This is why patriotism is important. If people can feel a sense of patriotic duty, the state does not have to direct their affairs so much. People will be motivated to do things voluntarily out of love for the society and one's fellows. When love runs out and people lose their motivation to do what is right, then you have a state with the stick to keep people in line.
So, getting back to drug policies, there is no 'perfect law' because the law itself is an acknowledgement of human failure. Humans will always be tempted to get stoned because this is how we are wired: we want to escape our pain, and will take the easiest way out.
Throwing people in jail is just the same as allowing people to get as high as they can get, because neither condition leads to healing. The father who is in jail is just as absent as the father who is hammered all the time. A 'functional' alcoholic or addict is still 'dysfunctional' even if he or she can keep a job and refrain from passing out in a public place.
That is because the real costs of addiction are in families, and the state has little control over families outside of divorce court and domestic violence calls. The latter is also devolving into a complete disaster.
Drug policies need to switch focus: instead of trying to figure out when and for how long to throw people in jail or let them use, why don't we start looking at the social perception of drugs? People complain that too many minorities are going to jail over drugs. The question is, why would people in a minority community think that taking drugs is a good idea when it makes their lives suck even more than they already do? Are they genetically incapable of making a rational decision to stop engaging in a self-destructive behavior?
No, it has nothing to do with genetics and everything to do with culture. Here is an example: I recently heard a Dutch addictions treatment specialist talk about IV drug use, and how it is plummeting in Holland. Why? He said it was largely due to the fact that African immigrants, who are 'integrating' into the Dutch addict community, have strong taboos against needles. Their refusal to use needles, and their open disdain for IV drug users, has pressured even white addicts to stop using IV drugs!
It is culture.
So long as we popularize the drug culture (for example, blacks listening to 'gangster rap' or whites listening to Grateful Dead or both of them listening to reggae), we are going to have drugs. If you make something 'cool,' people will do it. This is why you wore bell-bottom trousers and six-inch collars in the 1970s, and now look back at those photos and laugh. At the time, they were fashionable.
Of course, looking cool is more than just personal taste, but is driven by the need to be accepted. Drugs can look fashionable, but they are driven by the need to self-medicate. The modern drug culture just makes hiding your problems look good.
Until we as a society start to take this seriously and begin to self-censor our cultural influences, we will continue to have problems. America used to have huge marijuana fields for use in the hemp rope industry. Folks even knew you could 'smoke rope'... but they didn't. Why? Because is was socially unacceptable.
Now, it is, and so we have a problem. People are not ashamed to have a marijuana sticker in their cars the same way they would be with having a bumper sticker that says, "I ♥ Child Porn." Social acceptability is the difference.
The social costs of allowing drugs to be acceptable is that we are constantly fighting over them. We are giving one another mixed messages, and then wondering why everyone, particularly the young, is confused.