"Alcohol and tobacco cause many more deaths in users than do drugs. Decriminalization would not prevent us from treating drugs as we now treat alcohol and tobacco: prohibiting sales of drugs to minors, outlawing the advertising of drugs and similar measures. Such measures could be enforced, while outright prohibition cannot be. Moreover, if even a small fraction of the money we now spend on trying to enforce drug prohibition were devoted to treatment and rehabilitation, in an atmosphere of compassion not punishment, the reduction in drug usage and in the harm done to the users could be dramatic.
This plea comes from the bottom of my heart. Every friend of freedom, and I know you are one, must be as revolted as I am by the prospect of turning the United States into an armed camp, by the vision of jails filled with casual drug users and of an army of enforcers empowered to invade the liberty of citizens on slight evidence," - Milton Friedman, in a 1990 open letter to Bill Bennett, big government conservative.
(Hat tip: Stuttaford.)