A handful of empirical studies have related changes in youth smoking to popular laws that penalise tobacco possession, use, and purchase (PUP). In this paper, we review the literature and outline reasons why PUP laws may be unlikely to reduce youth smoking significantly at the population level. In theoretical terms, we argue that PUP laws lack important features required for punishment to be effective in changing behaviour. In practical terms, PUP transgressions seem difficult to detect. Conceptually, there is potential for PUP laws to undermine conventional avenues of discipline, such as the parent-child relationship and the school environment. Strategically, PUP laws may divert policy attention from effective tobacco control strategies, relieve the tobacco industry of responsibility for its marketing practices, and reinforce the tobacco industry's espoused position that smoking is for adults only. To assist further debate and discussion, we identify research issues requiring attention.