Mill's harm principle is commonly supposed to rest on a distinction between self-regarding conduct, which is not liable to interference, and other-regarding conduct, which is. As critics have noted, this distinction is difficult to draw. Furthermore, some of Mill's own applications of the principle, such as his forbidding of slavery contracts, do not appear to fit with it. This article proposes that the self-regarding/other-regarding distinction is not in fact fundamental to Mill's harm principle; what he should have said is that intervention is permissible only to prevent non-consensual harm, regardless of where it falls. This explains both why some other-regarding conduct is immune to interventions and why some self-regarding conduct can be interfered with
