It is a common concern that the international system of investment protection is unevenly balanced, protecting investors against host State misconduct without providing remedies for the investors’ own misconduct. To address such concerns, there is a growing momentum to include investor obligations in investment treaties. Moreover, even absent such provisions, respondent States have invoked a variety of arguments in order to draw the attention of arbitral tribunals to investor misconduct. This chapter discusses three of such arguments, namely those based on legality requirements, the clean hands doctrine, and the notion of contributory fault. These three concepts have been employed by host States even if the applicable investment treaty did not contain an explicit provision addressing investor conduct. This chapter analyzes the similarities and differences between the three concepts and compares their status in current practice. It then discusses their application in three investment arbitrations that concerned the termination of prospective mining operations by host State authorities in response to local opposition. Since mining projects commonly involve large-scale investments with significant local impacts, they are prone to conflict between investors, local communities, environmental organisations, and host State regulators. When disputes arise from the complex interactions between these different actors, the parties are likely to blame each other for the ultimate failure of the investment. This chapter discusses whether legality requirements, the clean hands doctrine and the notion of contributory fault have helped tribunals to address such multi-faceted conflicts.