The Harm Principle takes its name from John Stuart Mill: “the only purpose for which power can be rightfully exercised over any member of a civilized community, against his will, is to prevent harm to others.”
Existing freedom indices mostly measure democracy and political pluralism. Few of them ask whether a peaceful adult can say something odious, own a rifle, buy their own medicine, or choose how to die. The Civil Liberties Index does.
We count all of these as civil liberties: the freedom to speak, to arm and defend yourself, to control your own body, to keep your affairs private, to associate and worship, to leave, and to keep your property and your liberty unless you are lawfully convicted.