Full Idea
Many laws of contemporary society are very hard to defend in terms of Mill's Liberty Principle, such as laws against duelling, incest between siblings, and euthanasia.
Gist of Idea
Liberty principles can't justify laws against duelling, incest between siblings and euthanasia
Source
Jonathan Wolff (An Introduction to Political Philosophy (Rev) [2006], 4 'Poison')
Book Reference
Wolff,Jonathan: 'An Introduction to Political Philosophy (Rev)' [OUP 2006], p.127
A Reaction
[He cites Chief Justice Lord Devlin for this] Being killed in a duel can cause widespread misery. Fear of inbreeding is behind the second one, and fear of murdering the old behind the third one. No man is an island.