It should be made clear that Mises was not a supporter of the natural rights perspective (what he called "natural law".)
From Human Action:
"There is, however, no such thing as natural law and a perennial
standard of what is just and what is unjust. Nature is alien to the idea
of right and wrong. "Thou shalt not kill" is certainly not part of
natural law. The characteristic feature of natural conditions is that
one animal is intent upon killing other animals and that many species
cannot preserve their own life except by killing others. The notion of
right and wrong is a human device, a utilitarian precept designed to
make social cooperation under the division of labor possible."
"From the notion of natural law some people deduce the justice of
the institution of private property in the means of production. Other
people resort to natural law for the justification of the abolition of
private property in the means of production. As the idea of natural
law is quite arbitrary, such discussions are not open to settlement."
From Mises: The Last Knight of Liberalism by Jörg Guido Hülsmann:
"Traditionally, the champions of democracy had defended thisI'm with Mises on this.
political form with the help of arguments rooted in ethics or
natural law. All men are born equal, they claimed, and therefore
all men should be equally involved in political decision-making.
But this could only be realized in a democracy. Mises did not
find this line of reasoning convincing. He believed it was rather
obvious that all men were born unequal, and he had little
patience with arguments based on claims about natural law,
which he considered to be a fiction of the intellect. No agreement
could ever be reached on a fiction. Rather, it was to be
expected that everybody made up his own version of “natural”
law, to buttress his political agenda. Thus natural-law considerations
were simply unfit to be applied in politics, because the
very point of politics was, from Mises’s perspective at any rate,
to resolve conflicts."