Paternalism is defined as an action that infringes a person’s liberty and is performed without their consent, but is intended to improve a person’s welfare. As such, many public health policies are criticized as being paternalistic because they attempt to influence citizens’ behaviours to prevent disease or injury. Therefore, public health advocates ought to be aware of what justifies paternalism. Arguments based on the harm principle are the strongest defense of paternalistic policies in Western culture, but reinforcing an individual’s integrity and improving social welfare may also be considered sufficient reasons. In practice, what is considered sufficient reason for paternalism depends upon the culture of the affected society. Collectivist cultures are willing to accept a paternalistic policy in exchange for a better quality of life for their whole community, but individualist cultures are very averse to such a trade. This article provides examples of how these principles arise in the debate over implementing anti-obesity legislation. Advocates must recognize paternalism and know when it is acceptable in order to defend public health policy from that common criticism.