What is the role of legal ambiguity in the creation and institutionalization of private property regimes? In what ways does the (ab)use of legal ambiguities affect market-making processes? I address these questions through a detailed analysis of two large-scale urban renewal projects in Istanbul that impose a formal private property regime on informal settlements. My research reveals that without the strategic utilization of legal ambiguities and administrative arbitrariness by public and private actors, private property cannot be easily created and hence capitalist markets cannot function efficiently. My findings challenge the assumptions of several social science traditions such as neoclassical and neoinstitutionalist economics, as well as most works within the law and economics tradition regarding the relationship between law, property and economic development. These approaches to economic development are underpinned by the legal certainty that private property entails as the most important element for an efficient economic order. However, in their unconditional support for private ownership, they fail to realize the degree of legal ambiguity and administrative arbitrariness needed to create the private property regime in the first place. As such their arguments remain theoretically and empirically incomplete. A more complete analysis of the relationship between law and economic dynamics must focus on how private property is constructed, and the extent to which legal ambiguities and loopholes are utilized in this process.