>What "mythical natural law" would that be?

Assuming you're not being sarcastic:
Natural law theory is the idea that there are moral standards/laws that can be objectivly derived from nature. Natural law isn't made up by humans but "discovered" (Rand's "absolute morality" is an example of this). Then, one can "scientifically" derive natural rights from this. So (capitalistic) property rights come from the same infallible source as freedom of speech etc.