For some time now, it has seemed to me that laws against recreational drugs were an attempt to protect people from themselves. This alone makes the drug laws unwarranted, and an immoral intervention into the personal rights and responsibilities of individuals. Furthermore, if we look at the drug abuse problem, it seems obvious to me that either addiction is real, and drug abusers need medical help, or it's not real, and it really is a matter of personal choice. Addiction might undermine personal responsibility, but neither possibility justifies criminal prohibition.
How will jail time and confiscation of personal property help the drug abuser? And why should such penalties be applied to responsible drug users who do not have an abuse problem? Exactly who is being harmed by these activities? Even if you say friends and families are being "harmed", that still doesn't justify the penalties. After all, does it make any sense that the way to save the "destruction of families" is to do just that: destroy the family?
Furthermore, after spending some time with a drug addict who can't seem to help herself, I'm more convinced than ever that criminal prosecution is a stupid way of dealing with the problem. In an old column (from the 90s, IIRC), George Will once wrote about drugs that it was better to have a localized criminal problem than a generalized social problem. Nice try, George, but the trouble with "localized criminal problems" is that they tend to not stay "localized". Even as a criminal problem, it is still also a social problem, but the criminal laws make it harder to deal with as a social problem. Also, these drug laws are diverting law enforcement efforts away from their legitimate function of protecting individual rights, providing us all with less general protection. Thus, the drug laws themselves are hurting society in general.
One other thought has occurred to me, besides the "friends and family" argument. Given that drug users are perceived as unproductive or underproductive members of society ("slackers"), it may be that the justification for drug laws is the productivity of society, that drug users are harming society by not being more productive. This is more of a communitarian argument, and depends upon the belief that the individual must be subservient to the community as a whole, or at least, that individual rights are no greater than the needs or rights of the community as a whole, and need to be balanced.
Once brought out in the open, this argument is easy to demolish. Wasting law enforcement resources on recreational drug users does nothing to make the community more productive. It also assumes that individual rights and society in general are in conflict, which is itself an unexamined and I think unwarranted assumption: the rights of the individual and the interests of the community are properly complementary to each other, and not necessarily antagonistic--the community is simply a bunch of individuals with certain things in common, like locality or interests. Finally, there are plenty of other unproductive or underproductive people in society, and they are not criminalized. In fact, some of them are "rewarded" for being unproductive: welfare recipients, farmer subsidies, corporate bailouts, etc.
The real problem in dealing with the communitarian argument may be making people aware that they are holding these assumptions in their subconscious, and not recognizing them as assumptions.
Ending drug prohibition (the War on Drugs) won't solve the drug problem by itself, but it will stop creating additional, unintended problems for us, making it harder and more intractable for society to deal with. Ending the assumptions about drugs and drug use is a good place to start towards ending drug prohibition.