The presentation revolved around the regional approach of the Inter-American Court of Human Rights (IACtHR) to jus cogens in South America. Although Article 53 of Vienna Convention on the Law of Treaties (VCLT) indicates certain norms as peremptory norms jus cogens, the origin of these norms remains ambiguous. This uncertainty has encouraged scholarly debate on the nature of these norms. The interest in this topic was recently sparked by the Draft Conclusions on Peremptory Norms of General International Law by the International Law Commission (ILC). The conclusions preclude different interpretations and applications of jus cogens norms in the regional context, with most states reluctant to promote regional diversity as well.

The case law of the IACtHR offers a different perspective on the notion of regional jus cogens. This concept is not used explicitly by the IACtHR. However, Professor Lima argues that the IACtHR endorses this approach. He compared the scope of jus cogens norms as defined by the ILC and the IACtHR. The latter was shown to be more generous both in its determination and interpretation of jus cogens. For example, when reflecting on the prohibition of crimes against humanity, the IACtHR determined that ‘associated obligations to prosecute, investigate and punish such crimes’ also constitute jus cogens. This curious stance shows the IACtHR’s ambition to ensure that human rights standards remain applicable even where states decide to withdraw from the American Convention and the OAS Charter. However, it also causes tension with Article 53 VCLT, which defines that jus cogens norms must be recognised by the international community.

The presentation by Professor Lima was followed by a compelling discussion on the notion of regional jus cogens as developed by the IACtHR. Some referred to this concept as an oxymoron: where we may have regional customs subject to certain circumstances, it remained unclear whether the IACtHR can derive custom in its case law. Furthermore, it was argued that the IACtHR is not entitled to unilaterally determine the special character of specific norms where the consensus of the international community as a whole is missing. Some also drew a comparison between the IACtHR and other courts which also adopt a broad interpretation of jus cogens norms, including the position of Swiss courts regarding the principle of non-refoulment. Hence, some participants of the seminar indicated the dilemma of regional jus cogens stretches far beyond the South American region.

In response to these enquiries, Professor Lima clarified that there might be universal value in what he identifies as a regionalist approach. Certain values are more prominent in the South American continent due to the particular developments after the Second World War. He further elucidated that the ‘regional value’ does not eliminate the possibility of universal value. Moreover, it was stipulated that the case law of the International Court of Justice (ICJ) supports the notion of regional customs, which does not require the examination of state practice and opinio juris in different regions. This stance of the ICJ could be seen as encouraging the emergence of regional peremptory norms.

We are thankful for the visit of Professor Lucas Carlos Lima.