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School of Law

Thomas Lehmann


PhD Student



Thesis title

How will investment arbitrators balance investors’ rights with regulations taken by states in response of Covid-19 or climate change?


Dr Daniel Behn and Dr Matthieu Burnay

Summary of research

Investor-State Arbitration (ISA) is one of the most effective legal tools to attract foreign investors, resolve disputes effectively and improve international law and relations. However, some critics argue that this conflict resolution mechanism undermines the state’s right to regulate, notably in the protection of the environment and public health. Recent developments have shown a growing attention to the Police Powers Doctrine, which customarily safeguards public interest regulations from foreign investors’ claims to compensation. In the context of a pandemic, increasing international environmental treaties, rising security issues, how can Police Powers Doctrine bring solutions to legal issues and ultimately enhance the legitimacy of Investor-State Arbitration?

To answer this question, the research seeks to determine the fair balance between the right to regulate in the general interest and the protection of foreign investors’ rights through the Police Powers Doctrine. This endeavour will provide a theoretical foundation for a broader understanding of Police Powers Doctrine as part of international law. The study thus contributes to the research on the legitimacy of ISA and IIA, grounded in the general conception that arbitration’s role is in furthering harmonious international law and the rule of law.


Thomas Lehmann comes from a solid International Law background with a strong interest in Investor-State Arbitration and a passion towards research and strategy. His academic and professional background spreads from Berlin, to Paris, Toulouse, Hong Kong and London.

Thomas Lehmann was awarded his Master 2 and LLM (summa cum laude) by the University of Paris Sorbonne and City University of Hong Kong. His Master Thesis dealt with the use of Police Powers Doctrine in International Investment Law. He also holds the degrees of Bachelor in Law (Paris Sorbonne University), Bachelor in History and Political Sciences (Humboldt University Berlin), Master 1 in International Law (Toulouse-1 Capitole) and studied at King’s College London under an Erasmus Exchange Scholarship.

Thomas Lehmann caried out three internships in specialized law firms, worked as parliamentarian assistant in the French Parliament for one year and acts today as consultant in international arbitration.


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