Until 1970, psychoactive drugs were regulated at the federal level by a patchwork of statutes enacted since the turn of the century. These statutes were shaped by an evolving conception of congressional power under the U.S. Constitution. The first federal law on the subject was the Pure Food and Drug Act of 1906, which required the labeling of substances such as patent medicines if they included designated NARCOTICS (e.g., OPI-ATES and COCAINE) and were shipped in interstate commerce. In 1909, Congress banned the importation of smoking opium. Then in 1914, in the HARRISON NARCOTICS ACT, Congress deployed its taxing power as a device for prohibiting the distribution and use of narcotics for nonmedical purposes. (The taxing power was used because U.S. Supreme Court decisions implied that Congress would not be permitted to use its power to regulate interstate commerce in banning "local" activities...