In four independent Chapters, I examine how norms guide our behavior in an uncertain world. Methodologically, I apply the toolbox of experimental economics to research questions that are on the interface between economics and law (especially Chapter 1 and Chapter 2), sociology (especially Chapter 3), and social psychology (especially Chapter 4). Chapter 1 experimentally explores the effect of a provision from German copyright law – the so-called “Bestseller Paragraph” on market prices, on the number of deals struck and on perceived fairness. The results show that the provision leads to lower prices for copyrights, more copyrights trade, and the buyers express less ex-post discontent. Chapter 2 tests the effect of customary law on cooperatio...