Since the Supreme Court in recent decades has transformed the Commerce Clause into a license for federal intervention in all manner of economic activity, it may be fruitless to note that the Constitution does not authorize Congress to regulate intrastate sales of tobacco. It is nevertheless true, and what Congress is not empowered to do it surely may not delegate to the Food and Drug Administration.

Such old-fashioned concerns aside, the sort of regulations the FDA has proposed would not make much of a dent in underage smoking. Every state already forbids cigarette sales to minors. Enforcement is lax in many places, but simply duplicating the rule at the federal level is not likely to change that.

Restrictions on advertising and promotion are hard to square with the First Amendment, and there is little reason to believe they would have a noticeable impact on the level of cigarette consumption. The 1994 surgeon general’s report, which focused on underage smoking, acknowledged the "lack of definitive literature" in this area. None of the widely publicized studies that have appeared in recent years, including the much-hyped Joe Camel research, actually measured the impact of advertising on a teenager’s propensity to smoke.

Giving the FDA jurisdiction over tobacco could lead to other mischief. The agency has seriously considered forcing tobacco companies to gradually eliminate nicotine from cigarettes. This would make the habit more dangerous, since people would tend to smoke more to compensate for lower nicotine delivery, and it would invite a black market in full-strength cigarettes.

Proponents of FDA regulation may be sincere when they insist it is not a prelude to prohibition, but history suggests caution. Early in this century, cigarettes were banned in 19 states. The motivation then, as now, was to save the children.