Full Idea
When we call anything a person's right, we mean that he has a valid claim on society to protect him in the possession of it.
Gist of Idea
A right is a valid claim to society's protection
Source
John Stuart Mill (Utilitarianism [1861], Ch.5)
Book Reference
Mill,John Stuart: 'Utilitarianism (including On Liberty etc)', ed/tr. Warnock,Mary [Fontana 1962], p.309