It took years to overcome the tobacco industry’s resistance to regulation by the federal Food and Drug Administration, an impasse that was finally broken by defining cigarettes as a “nicotine delivery device.” What seemed an artful redefinition is suddenly appropriate, as the FDA has taken on the task of regulating the newly popular e-cigarettes, a device for delivering nicotine, not smoke, to the bodies of users. That distinction is important, to the public, and especially to public health advocates with an inclination to stamp out anything that looks or feels like a cigarette. Nicotine is the addictive substance delivered by burning tobacco, but it’s the other ingredients in the smoke that cause cancer and other diseases. There’s no tobacco in e-cigarettes, and no burning. E-cigarettes deliver nicotine, but don’t put the toxins that come from burning tobacco into the lungs or the air around the person using them. Does that mean e-cigarettes are safe? Not necessarily, since there hasn’t been much research done on the effects of vaporized nicotine. But the default position for government should be to permit products adults wish to purchase, not prohibit them because someone might someday discover they are bad for you. But nicotine is certainly addictive, and that’s bad for children. Adolescents are especially susceptible to nicotine addiction, and both law and common sense require adults to protect them from an expensive habit they might struggle to overcome their entire lives. Proposed rules announced by the FDA Thursday would prohibit the sale of e-cigarettes to anyone under 18 and require photo IDs for their purchase. It would apply the same limits to tobacco products – including pipe tobacco and cigars - that have slipped around restrictions on cigarettes. The rules would also require all makers of nicotine-delivery products to disclose to regulators their ingredients, manufacturing processes and scientific data, which is also sound public health policy. We can expect arguments from those who sell these products that they go too far, and arguments from anti-tobacco activists that they don’t go far enough. The FDA should consider limiting broadcast advertising and marketing to children, and perhaps limit the sweet flavorings in some e-cigarette products said to be aimed at hooking young people. Some municipalities and states are going much further, banning indoor and even outdoor use of e-cigarettes, even though the rationale for such bans – protecting non-smokers from secondhand smoke – doesn’t apply to e-cigarettes. If nicotine, as opposed to tobacco, is the enemy, shouldn’t they apply the same rules to nicotine gum and nicotine patches? E-cigarettes have the potential to be just as effective as gum and patches in helping adults control or kick the cigarette habit. The FDA has wisely stopped short of restrictions on their use by adults. Other agencies should do the same.