The issue of damages under investment treaties is attracting increased attention and critique. Large claims by investors - which often are for hundreds of millions or billions of dollars -- have raised both concerns and questions about the policy aims such awards serve. Concern is also growing about states being punished for necessary responses to crises such as COVID and climate change. In this context, Emma Aisbett (Australian National University) and Jonathan Bonnitcha (University of New South Wales) use a law-and-economics approach to propose a new rule for compensation that limits compensation to that required to prevent investment deterring effects of opportunistic host behavior, thus seeking to better ensure treaty participation benefits both source and host countries. In this event, Emma will present the proposal; Jeffrey Sachs (Columbia University) and Kekeletso Mashigo (Government of South Africa) will discuss it; and we will then open the event for questions and answers from participants. David Gaukrodger (OECD) will moderate.