J.S. Mill’s famous essay On Liberty proposes a broadly Utilitarian principle to be applied for the purpose of the preservation of individual liberty against state coercion. This principle is known as the ‘harm principle’. Mill provides three vaguely distinct formulations of the principle, and in each one, the term ‘harm’ takes on a slightly different meaning. The first formulation implies a definition of harm as an act which would require either individual or collective ‘self-protection’ as a response.