2026 PAW: Affaires D’Etats Vol. 5: Getting Causation Right in Investment Disputes

Key Takeaways

• Claimants often use “all‑or‑nothing” DCF valuations for unbuilt projects.
• Tribunals frequently accept speculative loss‑of‑opportunity arguments, risking inflated awards.
• Respondent states must rigorously challenge causation to avoid costly post‑award litigation.
• Weak damages evidence leads tribunals to request revised valuations, extending proceedings.
• Improper causation analysis can trigger high‑cost court challenges, as in Kazakhstan.

Pulse Analysis

Investor‑state dispute settlement (ISDS) has become a cornerstone of cross‑border investment protection, yet the legal concept of causation remains a gray area that can make or break an award. In arbitration, causation links a state’s alleged breach to the investor’s loss, separating genuine harm from ordinary commercial risk. The Paris Arbitration Week webinar highlighted how tribunals grapple with abstract counterfactuals, especially when projects never materialise or remain unprofitable for years. By dissecting recent cases, the panel showed that a rigorous causation analysis is essential to preserve the legitimacy of the ISDS system.

Claimants increasingly rely on “all‑or‑nothing” discounted cash‑flow models and loss‑of‑opportunity arguments to inflate quantum. Such approaches often rest on optimistic assumptions about regulatory approvals, financing and technical feasibility, turning the causation test into a speculative exercise. Tribunals, eager to provide remedies, sometimes accept these speculative chains, citing precedents like Crystallex to justify flexible quantification. This trend risks rewarding hypothetical profits that never had a realistic chance of materialising, prompting states to develop more robust evidentiary strategies and to demand alternative damage calculations.

For respondent states, the stakes are high. Failure to adequately contest causation can lead to awards that are later overturned in national courts, as seen in the World Wide Minerals v. Kazakhstan case, where inadequate causation reasoning resulted in costly rehearings and legal uncertainty. The panel urged states to present detailed causal analyses, challenge speculative assumptions early, and prepare for potential post‑award litigation. By doing so, they can limit exposure, reduce arbitration duration, and maintain the credibility of the ISDS framework.