Global Governance Centre
Paths Panel IV-1, November 2020

Paths Panel IV - Letting External Norms in: How Do Courts Behave When Reviewing Environmental Norms?

Ezgi Yildiz, Chanya Punyakumpol, Carlos Antonio Cruz Carrillo at the Graduate Institute, Geneva
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How do courts treat norms that are external to their foundational document?

In this paper, we seek to understand the way international courts develop external norms – subject matters that are not explicitly mentioned in, or otherwise not the main objectives of, their constitutive treaties. Applying a tripartite typology, we assess whether they tend to proactively develop the norm and encourage judicial cross-fertilization (i.e. acting as entrepreneurs), or apply established reasoning introduced in previous rulings (i.e. acting as arbitrators), or issue evasive rulings and employ judicial economy (i.e. acting as delineators). In so doing, we analyze whether they act entrepreneurial or deferential and we distinguish deference to legal authorities from deference to states. We analyze the patterns of judicial behavior looking at the case of environmental norms across three fields of international law, namely trade, human rights, and law of the sea.

In particular, we evaluate the case law of the Appellate Body of the World Trade Organization (the AB), the Inter-American Court of Human Rights (IACtHR), and the International Tribunal of the Law of the Sea (ITLOS). We employ a mixed method: relying on content analysis to categorize judicial behavior, using a social network analysis to visualize the relationship of judicial decisions across three regimes, and supporting our findings with a traditional doctrinal approach. Looking at these courts’ judicial behavior and citation patterns, we find a correlation between the two.

Our findings also indicate that each regime portrays a dominant judicial character and an idiosyncratic approach to environmental norms. While the AB is predominantly deferential to the authority of the previous decisions, the IACtHR is an eternal entrepreneur for environmental norms, and for their cross-fertilization across different fields of International Law. The ITLOS, on the other hand, employs judicial economy when it can and shows deference to states.

This exploratory research sheds light not only on the link between judicial behavior and citation patterns, but also on diverging and converging judicial strategies when addressing environmental norms.


  • Ezgi Yildiz, Postdoctoral Researcher at the Global Governance Centre, the Graduate Institute, Geneva
  • Chanya Punyakumpol, PhD Candidate, International Law and Research Assistant at the Center for Trade and Economic Integration, the Graduate Institute, Geneva
  • Carlos Antonio Cruz Carrillo, Research Assistant at the Global Governance Centre, the Graduate Institute, Geneva


  • Mark Pollack, Professor of Political Science and Law and Jean Monnet Chair, Temple University


  • Nico Krisch, Professor of International Law, The Graduate Institute, Geneva



This event is organised by the Global Governance Centre and is part of the ERC funded research project "The Paths of International Law".