This essay focuses on two specific aspects of knowledge that make it interesting from the viewpoint of law and economics. First, we consider the nature of knowledge as a public good, discussing how non-excludability, non-rivalry, and positive externalities in knowledge production affect private incentives and generate a demand for state intervention. We discuss the role of patent and copyright laws, as well as other forms of state support, in this context. Secondly, considering knowledge as information, we examine the economic implications of asymmetries in information, and the extent to which laws and the legal mechanism can help solve the problems created by asymmetric information.