The U.S. "schedule" drug-classification system derives from the agreements of the U.N. "Single Convention on Narcotic Drugs, 1961", as amended by the "1972 Protocol Amending the Single Convention on Narcotic Drugs, 1961". I don't have much experience interpreting U.N. resolutions, so I can't say whether the treaty's legalese approximation of spaghetti-code is normal. One thing that's clear is the U.N.'s presumption of authority to classify specific substances. The most recent official classification publication is from March 5, 1990, as determined by the U.N. Commission on Narcotic Drugs1. Here, cannabis appears in both Schedule I and Schedule IV.

A twist developed in 1971 with the U.N. Convention on Psychotropic Substances. Technically (pharmacologically), a "narcotic" is an opium derivative or synthetic that behaves like an opium derivative. Cannabis is not opiate in nature; it really doesn't belong in the narcotic group any more than, say, caffeine. The Psychotropic convention may be seen as an attempt to reconcile policy with nomenclature. In the schedules of the Psychotropic convention, cannabis and derivatives are Schedule I, except for the synthetic Dronabinol, which is Schedule II2.

The absence of alcohol and tobacco from the Schedules is indeed disturbing; the U.S. Center for Disease Control (CDC) fatality statistics for 1997 (most recent year available) show alcohol induced 19,576 deaths, while "drugs" induced only 15,973 deaths, nationwide3. Clearly, in the U.S. at least, alcohol alone is responsible for more deaths than all other drugs of recreation and abuse.

1. U.N. narcotic drug schedules,
2. U.N psychotropic drug schedules,
3. "Deaths: Final Data for 1997" by Donna L. Hoyert, Ph.D.; Kenneth D. Kochanek, M.A.; and Sherry L. Murphy, Division of Vital Statistics. National Vital Statistics Reports, Volume 47, Number 19 (June 30, 1999)