The claim that force and coercion are only permissible when necessary to protect individuals from initiatory force and coercion is at the heart of deontological or natural rights approaches to libertarianism. This chapter will give an overview of this rather austere ethical system, the political-economic commitments that flow from it, and some challenges to it. I will discuss the three main theories of political legitimacy that are self-conscious applications of this view: the consent theory, Nozick’s invisible hand theory, and market anarchism. I will then discuss potential tensions with private property rights; the moral status of the marketplace, and the potential egalitarian grounds for the parsimony of the approach.