This entry focuses on the legitimacy of private property and analyzes the process of first appropriation. In particular, we examine and comment the different views on the origin of private property rights that have emerged through the history of economic and legal thinking, from Democritus to de Jasay. These views have been grouped in two broad categories: consequentialism and fundamental principles. Although consequentialism is now dominant among economists and inchoate in the legal profession, we observe that it is in fact an alibi for discretionary policymaking by the authority. By definition, fundamentalist approaches generate rules that limit discretion. However, we show that some fundamentalist views rest on questionable a priori statements. De Jasay’s argument based on the presumption of liberty is perhaps the only perspective that escapes this criticism.