Host states are waking up to the power of pleas based on contributory fault or investor misconduct in investment arbitrations. The host state may have flagrantly breached the applicable investment treaty, but it can effectively be saved if it can adduce evidence of the investor’s wrongdoing. ‘Saving’ might mean that the arbitral tribunal lacks jurisdiction, the investor’s claim is inadmissible, the host state’s liability is eliminated, or the remedies that the host state must make good on are substantially reduced. The question that this chapter tackles is: what is risky or wrongful conduct on the part of the investor relevant to jurisdiction, admissibility, liability, or remedies? The significance is not born out of an obsession for order, but a recognition that decisions on these questions have different legal consequences. To resolve the question, international investment law is conceived as a schematic through which the various pleas arising out of an investment dispute must navigate. In detailing this schematic, the proper scopes of jurisdiction, admissibility, liability, and remedies are clarified. What this reveals is that ‘defences’ are distinguishable from other types of rules and risky or wrongful conduct attributable to the investor is generally relevant to liability.