An update on the scientific evidence for and against the legal banning of disciplinary spanking.

In 2004, the Canadian Supreme Court upheld the right of Canadian parents to use open-handed swats to a child's buttocks to correct child misbehavior, but only as developmentally appropriate (i.e., between the ages of 2 and 12). Some social scientists believe that the Canadian Supreme Court did not go far enough. These researchers support total bans on physical discipline. Other social scientists support Canada's existing age-specific legislation. This commentary provides a concise overview of physical discipline research since 2004, emphasizing the methodological rigor of the research used to argue for and against total spanking bans. Advocates of total bans primarily cite reviews based on bivariate correlations and non-randomized methods known to be inherently biased against disciplinary actions (i.e., methods known to make all disciplinary responses to defiance appear harmful). In contrast, those who support Canada's existing legislation have systematically compared methods known to be inherently biased in opposite directions (i.e., harmful- and beneficial-looking), to demonstrate that the true average effect size of customary spanking on child outcomes is likely very near zero. These researchers also emphasize four randomized clinical trials in which spanking increased compliance in defiant preschoolers. Other issues discussed in this commentary are: the developmental trajectories for children who do not learn to comply with parental directives while they are young; and children's risk of assault in countries with and without total bans. We conclude that the most rigorous empirical studies and available crime statistics validate the appropriateness of Canada's existing legislation on disciplinary spanking.