In his book the Ethics of Liberty, Murray Rothbard sets out the links between individual liberty, property rights, and the non-aggression principle. Rothbard's explanation of property rights as the essence of liberty has greatly influenced the libertarian understanding of the NAP, but there is often a great deal of confusion as to what amounts to an act of aggression. As David Gordon has pointed out, some libertarians have gone so far as to say that the NAP should be rejected altogether for having "morally unacceptable implications."

One mistake many libertarians make is to suppose that theoretical principles can provide a complete resolution for difficult cases, in the sense that we should be able to ascertain—just by studying the NAP—whether it has been violated in specific cases. Gordon points out that this overlooks the role of other considerations, such as social conventions and legal norms, in resolving real world disputes. The "morally unacceptable implications" that many libertarians find disturbing are the result of theorizing about the NAP without regard to the broader ethical framework within which Rothbard defends property rights. Rothbard's theory of liberty is not just a philosophical or academic treatise based on a set of hypothetical problems. It is also a "system of libertarian law" designed as a foundation for "the truly successful functioning of what we may hope will be the libertarian society of the future."