THE LIBERTARIAN CREED rests upon one central axiom: that no man
or group of men may aggress against the person or property of anyone
else. This may be called the “nonaggression axiom.” “Aggression” is
defined as the initiation of the use or threat of physical violence against
the person or property of anyone else. Aggression is therefore synonymous
with invasion.
If no man may aggress against another; if, in short, everyone has the
absolute right to be “free” from aggression, then this at once implies that
the libertarian stands foursquare for what are ge nerally known as “civil
liberties”: the freedom to speak, publish, assemble, and to engage in such
“victimless crimes” as pornography, sexual deviation, and prostitution
(which the libertarian does not regard as “crimes” at all, since he defines a
“crime” as violent invasion of someone else’s person or property).
Furthermore, he regards conscription as slavery on a massive scale. And
since war, especially modern war, entails the mass slaughter of civilians,
the libertarian regards such conflicts as mass murder and therefore totally
illegitimate.
All of these positions are now considered “leftist” on the contemporary
ideological scale. On the other hand, since the libertarian also opposes
invasion of the rights of private property, this also means that he just as
emphatically opposes government interference with property rights or with
the free-market economy through controls, regulations, subsidies, or prohibitions.

For if every individual has the right to his own property
without having to suffer aggressive depredation, then he also has the right
to give away his property (bequest and inheritance) and to exchange it for
the property of others (free contract and the free market economy) without
interference. The libertarian favors the right to unrestricted private
property and free exchange; hence, a system of “laissez- faire capitalism.”
In current terminology again, the libertarian position on property and
economics would be called “extreme right wing.” But the libertarian sees
no inconsistency in being “leftist” on some issues and “rightist” on others.

Murray Rothbard, For a new liberty : the libertarian manifesto