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The Differing Application of the Principle of Nullum Crimen Sine Lege in International Criminal Tribunals and Human Rights Bodies

International Justice and Human Rights Unit – Research in Action

The international legal system as it exists today is fragmented and pluralistic in nature. The corpus of international law is comprised of various specialised legal fields, such as public international law, environmental law, and trade law. Each of these fields are codified by their own treaty regimes and have operational judicial bodies. Despite this, some fields intersect and have competence over the same or similar issues. Given that the legal system is structured in this way, legal principles and norms also frequently overlap with one another. Where overlapping occurs, there is a real possibility for norms to come into conflict with one another and produce clashes.

Holly Devlin’s doctoral thesis will consider this issue from the perspective of its impacts on norms of jus cogens. While jus cogens are required to be applied in a manner which is consistent across the board, there are various instances where peremptory norms have lacked consistent application across legal fields. This is problematic as it can detrimentally interfere with the clarity of these principles and has the potential to impact their high-level status. One example can be the legality principle (nullum crimen sine lege) and its application by international criminal tribunals and human rights bodies.

In many instances, norm conflicts are able to be overcome using various resolution tactics. A tactic which has often been employed by international actors in the past relates to the definitions and interpretations which are given to legal principles. For instance, each legal field may apply a marginally different variation of a legal rule depending on the aims or purposes of the field. However, this technique will not be appropriate for rules of jus cogens which must be applied in a uniform manner.

Holly Devlin’s doctoral thesis will suggest that the dual phenomena of judicial dialogue and cross-fertilisation may be a potential solution. Judicial dialogue occurs when courts look to jurisprudence made by other adjudicatory bodies to help them interpret the law in their own cases. Indeed, there has been a growing pattern in the case law of international courts where a greater willingness has been shown to apply decisions made by neighbouring courts. Consequently, this has allowed international courts to increasingly influence the law, decision-making, and jurisprudence of other adjudicative bodies. Where judicial dialogue has occurred between two courts, cross-fertilisation will result. Cross-fertilisation can be a positive occurrence as when interpretations of legal principles are shared between courts or legal fields, it leads to a greater sense of reliability within the system.

In the past, scholarship has identified where judicial dialogue and cross-fertilisation have occurred and why. However, in this thesis, it will take a step further and suggest that judicial dialogue and cross-fertilisation should be used as a tool by judges sitting in international courts whenever they encounter a conflict.