If there is a single principle by which I live – it is:
“No one may threaten or commit violence (“aggress”) against another man’s person or property. Violence may be employed only against the man who commits such violence; that is, only defensively against the aggressive violence of another…Most Libertarians and even Conservatives are familiar with the rule and even defend it; the problem is not so much in arriving at the rule as in fearlessly and consistently pursuing its numerous and often astounding implications. “
Murray Rothbard- from the essay War,Peace, and The State in his book: Egalitarianism as a Revolt Against Nature, and Other Essays