This course will discuss law and economics approaches to public international law. The focus is on insights garnered by applying the economics toolkit to legal issues, rather than doctrinal analysis. Legal rules will only be the starting point of our inquiry. We will ask about the effects of current and potential rules as well as the reason for the existence of these rules. Rather than studying economics, we will apply (micro-)economic methods, which are not limited to issues of the (international) economy. We will cover a wide range of topics – from the sources of public international law to the use of force and international environmental law.