It is a fact, IMHO, that a punitive approach, while remaining constitutional, to the drug problem does not work. We either have to raise the punishment to levels so severe that no one dares break the drug laws, or we have to adopt an approach that isn't punitive. Countless research turns up the same results year over year: restricting access to drugs does not achieve the desired ends.
I worry far less about addiction than I do about the violence that the war on drugs causes. There will always be addicts. It's the generations of fathers and sons lost to the violence and prison, and the ghettoizing of once strong neighborhoods via gang control that are the bitter fruit of Nixon's war.
If we believe that sociologists should strive to only recommend objective policy to politicians, it would seem that the overwhelming consensus of the last 25 years is that a "punitive" approach to drug policy is a failure, and that other avenues should be attempted, especially with regard to marijuana. However, the consensus about the outcomes of that change is not in any way agreed upon, they just agree that a punitive approach carries far more repercussions in society that most believe carry a larger negative impact than increased availability of legalized production, sale, purchase, and consumption.
Here are some links (with quantitative data that talk more about what I'm contending).