Speaker: Dr Penelope Ridings, International Law Commission

Lecture summary: In the last several decades, scholarly views of due diligence in international law have shifted from due diligence as a primary obligation under customary international law, to due diligence as a standard of conduct attached to a primary obligation. Thus, for example, due diligence is required to meet a State’s obligation of protection (of the environment) or of prevention (of genocide). The International Court of Justice in its Advisory Opinion on Climate Change adopted such an articulation and stated that due diligence is a standard of conduct and States have a duty to prevent significant harm to the environment by acting with due diligence. The Court not only reinforced the importance of the customary international law obligation not to cause significant harm to the environment but placed this within the ‘no harm’ principle, as expressed in the Corfu Channel case. However, the Court did not expressly articulate whether there was a broader obligation of due diligence that applies not only to the prevention of environmental harm, but also to the prevention of other harms to the rights and interests of States. Due diligence is thus as a crossroads. Has the ICJ essentially sought to bridge the gap between on the one hand the notion of due diligence as an obligation on a State not to permit activities subject to its jurisdiction or control which causes harm to the rights and interests of other States, and on the other hand the notion of due diligence as a standard of conduct attached to a primary obligation? Has the Court opened the door to finding a general customary international law obligation not to cause harm to the rights and interests of other States? Or has it confined due diligence to its status as a standard of conduct attached to a primary obligation? This lecture will discuss this pivotal point which is central to the elucidation of the foundation and scope of the due diligence obligation under international law.

Dr Penelope Ridings is a Member of the International Law Commission and New Zealand Barrister practising in the field of public international law. In 2025 she was appointed the ILC Special Rapporteur for the topic ‘Due Diligence in International Law’. She was formerly New Zealand’s Chief International Legal Adviser in the Ministry of Foreign Affairs and Trade and a New Zealand diplomat. She was Agent for New Zealand before the International Court of Justice in Whaling in the Antarctic: Australia v Japan, New Zealand Intervening and before the International Tribunal on the Law of the Sea in the Request for an Advisory Opinion submitted by the Sub-Regional Fisheries Commission.

After moving to the New Zealand Bar, she has advised governments and international organisations on public international law including law of the sea, fisheries, environmental law, trade and investment, international security and international dispute settlement. She was Chair of the 2025 arbitration under the EU-UK Trade and Cooperation Agreement (UK-Sandeel) and Chair of the WTO appeal arbitration China – Enforcement of Intellectual Property Rights under the Multi-Party Interim Appeal Arbitration Arrangement. She has served on several ICSID ad hoc Annulment Committees, including as Chair, and as an independent panellist in disputes before the WTO. She has lectured in international law and contributed to several books and written articles on various aspects of international law.

This lecture was delivered on 13 February 2026 and is part of the Friday Lunchtime Lecture series.

Speakers: Prof Mads Andenas & Prof Johann Ruben Leiss, University of Oslo

Lecture summary: The lecture explores the systemic function of general principles in international law in light of the ongoing work of the ILC on general principles of law and recent practice of international courts and tribunals, such as the Climate Change Advisory Opinion of the International Court of Justice from 2025. In its first part, the lecture examines the ILC’s approach to the systemic function of general principles and comments of states on the ILC’s work. In its second and third part, the lecture discusses the two main features of the systemic function of general principles, namely their contribution to inter-norm and inter-systemic coherence in international law. All general principles potentially fulfil a systemic function by their gap-filling role and inter-systemic communication through Article 38(1)(c) ICJ Statute. Several general principles have a systemic pull in inter-norm contexts as interpretative guidelines and inter-norm harmonisers and coordinators. In the relationship between different (sub)orders of international law (including European law and national legal orders applying international law), several principles provide for ‘hinge’ mechanisms and inter-system harmonisers which open legal (sub)orders to one another, and integrate them into (relative) unity, while others serve as inter-system coordinators or mechanisms for conditional closure of legal orders. This means, all general principles have a systemic function, whereas certain principles have more direct systemic function by virtue of their normative content. Through their systemic function, general principles contribute as a central cohesive force furthering international law’s character as a legal and (relative) unitary system. This system is characterized by a complex and dynamic interplay between a plurality of legal norms, orders, and sub-orders, including national legal orders, through systemic principles of openness, coordination, and conditional closure.

Chair: Prof Campbell McLachlan

This lecture was given on 6 February 2026 and is part of the Friday Lunchtime Lecture series at the Lauterpacht Centre.

Lecture summary: Empire is a big theme in international law. At the same time, the historical discussion on imperialism and international law had focussed primarily on the West European Empires. This presentation examines Russian and Soviet historical engagements with international law through imperial ideas and practices. Of the doctrines of international law, the ideas of state identity (continuity) and also termination of treaties via the doctrine of clausula rebus sic stantibus are examined, and how their use has served the imperial construction and practice of international law in Russia. Understanding the history of international law in Russia through the lens of Empire helps us inter alia to situate Russia's war against Ukraine.

Lauri Mälksoo is Professor of International Law at the University of Tartu in Estonia. He is member of the Institut de Droit International, of the Venice Commission of the Council of Europe and of the Estonian Academy of Sciences. He has published two monographs on the history and theory of international law in Russia and the Soviet Union at the Oxford University Press.

Chair: Prof Marc Weller

This lecture was given on 30 January 2026 and is part of the Friday Lunchtime Lecture series at the Lauterpacht Centre.

Speaker: Prof Antonios Tzanakopoulos, University of Oxford

No lecture summary available.

Chair: Prof Jan Klabbers

This lecture was given on 23 January 2026 and is part of the Friday Lunchtime Lecture series at the Lauterpacht Centre.

The speaker for the Eli Lauterpacht Lecture 2025 was Santiago Villalpando, Legal Advisor and Director of UNESCO.

Lecture summary: Is international law facing a decline of treaties?

In recent years, several authoritative voices have pointed out certain developments which seem to indicate that States are shifting away from treaty law-making for the governance of their international relations.

Taking as a starting point the sociological concept of “liquid modernity” introduced by Zygmunt Bauman, this lecture will explore how treaties, archetypes of solid and stable law-making, have reacted to an unstable global community where norms seem to be eroding and long-term commitments appear to be challenged.

As the lecture will show, there is no doubt that the law and practice of treaties have evolved to adapt to a shifting international environment, but the news about the death of treaties is greatly exaggerated.

The Eli Lauterpacht Lecture was established after Sir Eli's death in 2017 to celebrate his life and work. This lecture takes place on a Friday at the Centre at the start of the Michaelmas Term in any academic year.

These lectures are kindly supported by Dr and Mrs Ivan Berkowitz who are Principal Benefactors of the Centre.

Lecture summary: Over centuries and across continents, authoritarian governments have demonstrated a large appetite for international cooperation to target political opponents across borders. As the world’s premier body for international police cooperation, Interpol is not supposed to facilitate this kind of transnational repression -- and yet, in recent years, there is growing concern that authoritarian governments are abusing Interpol's tools. Interpol has taken meaningful steps to curb such abuse, but the durability of those protections is in doubt given the rising influence of authoritarian governments in that organization. The looming question is at what point universal multilateral cooperation with respect to law enforcement might cease to be viable.

Kristina Daugirdas is the Francis A. Allen Collegiate Professor of Law at the University of Michigan Law School. She teaches and writes primarily in the fields of international law and institutions.

Her scholarship currently focuses on international organizations, accountability mechanisms, and the ongoing evolution of the international legal system. She is a member of the editorial board of the International Organizations Law Review and the State Department’s Advisory Committee on International Law. She also serves as an adviser to the American Law Institute’s Restatement (Fourth) of Foreign Relations Law.

In 2016–2017, Daugirdas was a visiting fellow at the Graduate Institute of International and Development Studies in Geneva and served as a consultant on public international law issues for the World Intellectual Property Organization. From 2014 to 2017, she co-authored the Contemporary Practice of the United States Relating to International Law: A section of the American Journal of International Law. In 2014, she was awarded the Francis Deák Prize for an outstanding article published in the American Journal of International Law by a younger author.

Daugirdas has taken on significant leadership roles at the law school, including serving as Associate Dean for Academic Programming from 2021 to 2024. She also led a subcommittee of the Advisory Committee on the University of Michigan Principles on Diversity of Thought and Freedom of Expression.

Prior to entering academia, Daugirdas was an attorney-adviser at the State Department’s Office of the Legal Adviser, receiving multiple honors for her service. As an attorney-adviser, she provided guidance on the negotiation and implementation of UN Security Council sanctions and amicus participation by the US government in lawsuits with foreign policy implications.

Chair: Prof Fernando Lusa Bordin

This lecture was given on 7 November 2025 and is part of the Friday Lunchtime Lecture series at the Lauterpacht Centre.

Lecture summary: Most observers – at least in the West – agree that the twenty-first century has been particularly tumultuous. But while some explain the volatility of our times by reference to historical analogies, e.g. moments of power transition in the twentieth century, others claim that we are in a moment of polycrisis for which there is no precedent. In this talk I split the difference: mainstream International Relations is wrong to assume the twenty-first century will resemble the twentieth century, but there are other historical precedents we can use to better think about our current predicament.

Ayşe Zarakol is Professor of International Relations at the University of Cambridge (Emmanuel College). She is the author of After Defeat: How the East Learned to Live with the West (Cambridge UP, 2011) and Before the West: The Rise and Fall of Eastern World Orders (Cambridge UP, 2022), and the editor of Hierarchies in World Politics (Cambridge UP, 2017). Before the We has won six awards, including the SSHA and ISA annual best book prizes. In 2024, she was elected to fellowship in the British Academy and the Academia Europea. Also in 2024, she received an Honorary Doctorate from the University of Copenhagen. At the moment, Zarakol is overseeing an international research collaboration on Global Disorder funded by a British Academy Knowledge Frontiers Grant. She is also one of the two Associate Editors of International Organization. Her next book, Ozymandias, is a world history of strongmen, aimed at a general audience. This book is under contract with William Collins (UK) and Grove Atlantic (US).

Chair: Prof Surabhi Ranganathan

This lecture was given on 31 October 2025 and is part of the Friday Lunchtime Lecture series at the Lauterpacht Centre.

Harro van Asselt is the Hatton Professor of Climate Law with the Department of Land Economy, a Fellow and Director of Studies at Hughes Hall, and a Fellow with the Lauterpacht Centre for International Law, University of Cambridge. He is also Professor of Climate Law and Policy at the University of Eastern Finland Law School, and an Affiliated Researcher with the Stockholm Environment Institute.

The Hatton Chair is the first endowed professorship in climate law in the United Kingdom. The aim of the Chair is to advance research and teaching with a view to strengthening legal responses to the ongoing climate crisis.

The lecture was followed by a panel on 'The Prospects of Global Climate Law'

Co-organised by the University of Cambridge and LUISS.